diff --git a/src/OpenTelemetry.Abstractions/Metrics/DefaultMeter.cs b/src/OpenTelemetry.Abstractions/Metrics/DefaultMeter.cs
new file mode 100644
index 00000000000..c623f256ece
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/DefaultMeter.cs
@@ -0,0 +1,298 @@
+// <copyright file="DefaultMeter.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Net.NetworkInformation;
+    using OpenTelemetry.Metrics.Implementation;
+    using OpenTelemetry.Resources;
+    using OpenTelemetry.Tags;
+    using OpenTelemetry.Trace;
+
+    /// <summary>
+    /// No-op implementation of a meter interface.
+    /// </summary>
+    public class DefaultMeter : IMeter
+    {
+        private static CounterDoubleBuilder counterDoubleBuilder = new CounterDoubleBuilder();
+        private static CounterLongBuilder counterLongBuilder = new CounterLongBuilder();
+        private static GaugeDoubleBuilder gaugeDoubleBuilder = new GaugeDoubleBuilder();
+        private static GaugeLongBuilder gaugeLongBuilder = new GaugeLongBuilder();
+        private static MeasureBuilder measureBuilder = new MeasureBuilder();
+
+        /// <inheritdoc/>
+        public ICounterDoubleBuilder GetCounterDoubleBuilder(string name) => counterDoubleBuilder;
+
+        /// <inheritdoc/>
+        public ICounterLongBuilder GetCounterLongBuilder(string name) => counterLongBuilder;
+
+        /// <inheritdoc/>
+        public IGaugeDoubleBuilder GetGaugeDoubleBuilder(string name) => gaugeDoubleBuilder;
+
+        /// <inheritdoc/>
+        public IGaugeLongBuilder GetGaugeLongBuilder(string name) => gaugeLongBuilder;
+
+        /// <inheritdoc/>
+        public IMeasureBuilder GetMeasureBuilder(string name) => measureBuilder;
+
+        /// <inheritdoc/>
+        public void Record(IEnumerable<IMeasurement> measurements)
+        {
+        }
+
+        /// <inheritdoc/>
+        public void Record(IEnumerable<IMeasurement> measurements, ITagContext tagContext)
+        {
+        }
+
+        /// <inheritdoc/>
+        public void Record(IEnumerable<IMeasurement> measurements, ITagContext tagContext, SpanContext spanContext)
+        {
+        }
+
+        private class CounterDoubleTimeSeries : ICounterDoubleTimeSeries
+        {
+            public void Add(double delta)
+            {
+            }
+
+            public void Set(double val)
+            {
+            }
+        }
+
+        private class CounterDouble : ICounterDouble
+        {
+            private static CounterDoubleTimeSeries timeSeries = new CounterDoubleTimeSeries();
+
+            public void Clear()
+            {
+            }
+
+            public ICounterDoubleTimeSeries GetDefaultTimeSeries() => timeSeries;
+
+            public ICounterDoubleTimeSeries GetOrCreateTimeSeries(IEnumerable<string> labelValues) => timeSeries;
+
+            public void RemoveTimeSeries(IEnumerable<string> labelValues)
+            {
+            }
+
+            public void SetCallback(Action metricUpdater)
+            {
+            }
+        }
+
+        private class CounterDoubleBuilder : ICounterDoubleBuilder
+        {
+            private static CounterDouble counterDouble = new CounterDouble();
+
+            public IMetric<ICounterDoubleTimeSeries> Build() => counterDouble;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetComponent(string component) => this;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetConstantLabels(IDictionary<LabelKey, string> constantLabels) => this;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetDescription(string description) => this;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetLabelKeys(IEnumerable<LabelKey> labelKeys) => this;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetResource(Resource resource) => this;
+
+            public IMetricBuilder<ICounterDoubleTimeSeries> SetUnit(string unit) => this;
+        }
+
+        private class CounterLongTimeSeries : ICounterLongTimeSeries
+        {
+            public void Add(long delta)
+            {
+            }
+
+            public void Set(long val)
+            {
+            }
+        }
+
+        private class CounterLong : ICounterLong
+        {
+            private static CounterLongTimeSeries timeSeries = new CounterLongTimeSeries();
+
+            public void Clear()
+            {
+            }
+
+            public ICounterLongTimeSeries GetDefaultTimeSeries() => timeSeries;
+
+            public ICounterLongTimeSeries GetOrCreateTimeSeries(IEnumerable<string> labelValues) => timeSeries;
+
+            public void RemoveTimeSeries(IEnumerable<string> labelValues)
+            {
+            }
+
+            public void SetCallback(Action metricUpdater)
+            {
+            }
+        }
+
+        private class CounterLongBuilder : ICounterLongBuilder
+        {
+            private static CounterLong counterLong = new CounterLong();
+
+            public IMetric<ICounterLongTimeSeries> Build() => counterLong;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetComponent(string component) => this;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetConstantLabels(IDictionary<LabelKey, string> constantLabels) => this;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetDescription(string description) => this;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetLabelKeys(IEnumerable<LabelKey> labelKeys) => this;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetResource(Resource resource) => this;
+
+            public IMetricBuilder<ICounterLongTimeSeries> SetUnit(string unit) => this;
+        }
+
+        private class GaugeDoubleTimeSeries : IGaugeDoubleTimeSeries
+        {
+            public void Add(double delta)
+            {
+            }
+
+            public void Set(double val)
+            {
+            }
+        }
+
+        private class GaugeDouble : IGaugeDouble
+        {
+            private static GaugeDoubleTimeSeries timeSeries = new GaugeDoubleTimeSeries();
+
+            public void Clear()
+            {
+            }
+
+            public IGaugeDoubleTimeSeries GetDefaultTimeSeries() => timeSeries;
+
+            public IGaugeDoubleTimeSeries GetOrCreateTimeSeries(IEnumerable<string> labelValues) => timeSeries;
+
+            public void RemoveTimeSeries(IEnumerable<string> labelValues)
+            {
+            }
+
+            public void SetCallback(Action metricUpdater)
+            {
+            }
+        }
+
+        private class GaugeDoubleBuilder : IGaugeDoubleBuilder
+        {
+            private static GaugeDouble gaugeDouble = new GaugeDouble();
+
+            public IMetric<IGaugeDoubleTimeSeries> Build() => gaugeDouble;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetComponent(string component) => this;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetConstantLabels(IDictionary<LabelKey, string> constantLabels) => this;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetDescription(string description) => this;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetLabelKeys(IEnumerable<LabelKey> labelKeys) => this;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetResource(Resource resource) => this;
+
+            public IMetricBuilder<IGaugeDoubleTimeSeries> SetUnit(string unit) => this;
+        }
+
+        private class GaugeLongTimeSeries : IGaugeLongTimeSeries
+        {
+            public void Add(long delta)
+            {
+            }
+
+            public void Set(long val)
+            {
+            }
+        }
+
+        private class GaugeLong : IGaugeLong
+        {
+            private static GaugeLongTimeSeries timeSeries = new GaugeLongTimeSeries();
+
+            public void Clear()
+            {
+            }
+
+            public IGaugeLongTimeSeries GetDefaultTimeSeries() => timeSeries;
+
+            public IGaugeLongTimeSeries GetOrCreateTimeSeries(IEnumerable<string> labelValues) => timeSeries;
+
+            public void RemoveTimeSeries(IEnumerable<string> labelValues)
+            {
+            }
+
+            public void SetCallback(Action metricUpdater)
+            {
+            }
+        }
+
+        private class GaugeLongBuilder : IGaugeLongBuilder
+        {
+            private static GaugeLong counterLong = new GaugeLong();
+
+            public IMetric<IGaugeLongTimeSeries> Build() => counterLong;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetComponent(string component) => this;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetConstantLabels(IDictionary<LabelKey, string> constantLabels) => this;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetDescription(string description) => this;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetLabelKeys(IEnumerable<LabelKey> labelKeys) => this;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetResource(Resource resource) => this;
+
+            public IMetricBuilder<IGaugeLongTimeSeries> SetUnit(string unit) => this;
+        }
+
+        private class Measurement : IMeasurement
+        {
+        }
+
+        private class Measure : IMeasure
+        {
+            private static IMeasurement measurement = new Measurement();
+
+            public IMeasurement CreateDoubleMeasurement(double value) => measurement;
+
+            public IMeasurement CreateLongMeasurement(long value) => measurement;
+        }
+
+        private class MeasureBuilder : IMeasureBuilder
+        {
+            private static Measure measure = new Measure();
+
+            public IMeasure Build() => measure;
+
+            public IMeasureBuilder SetDescription(string description) => this;
+
+            public IMeasureBuilder SetType(MeasureType type) => this;
+
+            public IMeasureBuilder SetUnit(string unit) => this;
+        }
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/ICounterDouble.cs b/src/OpenTelemetry.Abstractions/Metrics/ICounterDouble.cs
new file mode 100644
index 00000000000..7694e10474f
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/ICounterDouble.cs
@@ -0,0 +1,28 @@
+// <copyright file="ICounterDouble.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using OpenTelemetry.Metrics.Implementation;
+
+    /// <summary>
+    /// Counter metric, to report instantaneous measurement of a double value. Cumulative values can go
+    /// up or stay the same, but can never go down.Cumulative values cannot be negative.
+    /// </summary>
+    public interface ICounterDouble : IMetric<ICounterDoubleTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/ICounterLong.cs b/src/OpenTelemetry.Abstractions/Metrics/ICounterLong.cs
new file mode 100644
index 00000000000..d1cb99a35d8
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/ICounterLong.cs
@@ -0,0 +1,28 @@
+// <copyright file="ICounterLong.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using OpenTelemetry.Metrics.Implementation;
+
+    /// <summary>
+    /// Counter metric, to report instantaneous measurement of a double value. Cumulative values can go
+    /// up or stay the same, but can never go down.Cumulative values cannot be negative.
+    /// </summary>
+    public interface ICounterLong : IMetric<ICounterLongTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IGaugeDouble.cs b/src/OpenTelemetry.Abstractions/Metrics/IGaugeDouble.cs
new file mode 100644
index 00000000000..b584fcfc2fa
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IGaugeDouble.cs
@@ -0,0 +1,28 @@
+// <copyright file="IGaugeDouble.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using OpenTelemetry.Metrics.Implementation;
+
+    /// <summary>
+    /// Gauge metric, to report instantaneous measurement of a double value. Cumulative values can go
+    /// up or down.
+    /// </summary>
+    public interface IGaugeDouble : IMetric<IGaugeDoubleTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IGaugeLong.cs b/src/OpenTelemetry.Abstractions/Metrics/IGaugeLong.cs
new file mode 100644
index 00000000000..6fd9c4d04ed
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IGaugeLong.cs
@@ -0,0 +1,28 @@
+// <copyright file="IGaugeLong.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using OpenTelemetry.Metrics.Implementation;
+
+    /// <summary>
+    /// Gauge metric, to report instantaneous measurement of a double value. Cumulative values can go
+    /// up or stay the same, but can never go down.Cumulative values cannot be negative.
+    /// </summary>
+    public interface IGaugeLong : IMetric<IGaugeLongTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IMeasure.cs b/src/OpenTelemetry.Abstractions/Metrics/IMeasure.cs
new file mode 100644
index 00000000000..bc4a6ee74d2
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IMeasure.cs
@@ -0,0 +1,35 @@
+// <copyright file="IMeasure.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    public interface IMeasure
+    {
+        /// <summary>
+        /// Records the measurement of this <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="value">Value to be recorded.</param>
+        /// <returns>Measurement representing this value.</returns>
+        IMeasurement CreateDoubleMeasurement(double value);
+
+        /// <summary>
+        /// Records the measurement of this <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="value">Value to be recorded.</param>
+        /// <returns>Measurement representing this value.</returns>
+        IMeasurement CreateLongMeasurement(long value);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IMeasurement.cs b/src/OpenTelemetry.Abstractions/Metrics/IMeasurement.cs
new file mode 100644
index 00000000000..90318f0ffe5
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IMeasurement.cs
@@ -0,0 +1,25 @@
+// <copyright file="IMeasurement.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    /// <summary>
+    /// Immutable representation of a measurement.
+    /// </summary>
+    public interface IMeasurement
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IMeter.cs b/src/OpenTelemetry.Abstractions/Metrics/IMeter.cs
new file mode 100644
index 00000000000..6043037ae9d
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IMeter.cs
@@ -0,0 +1,71 @@
+// <copyright file="IMeter.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using System.Collections;
+    using System.Collections.Generic;
+    using OpenTelemetry.Metrics.Implementation;
+    using OpenTelemetry.Tags;
+    using OpenTelemetry.Trace;
+
+    /// <summary>
+    /// Returns a builder for <see cref="ICounterDouble"/>.
+    /// </summary>
+    public interface IMeter
+    {
+        /// <summary>
+        /// Gets the builder for <see cref="ICounterDouble"/>.
+        /// </summary>
+        /// <param name="name">Name of the counter.</param>
+        /// <returns>The builder for the <see cref="ICounterDouble"/>.</returns>
+        ICounterDoubleBuilder GetCounterDoubleBuilder(string name);
+
+        /// <summary>
+        /// Gets the builder for <see cref="ICounterLong"/>.
+        /// </summary>
+        /// <param name="name">Name of the counter.</param>
+        /// <returns>The builder for the <see cref="ICounterLong"/>.</returns>
+        ICounterLongBuilder GetCounterLongBuilder(string name);
+
+        /// <summary>
+        /// Gets the builder for <see cref="IGaugeDouble"/>.
+        /// </summary>
+        /// <param name="name">Name of the counter.</param>
+        /// <returns>The builder for the <see cref="IGaugeDouble"/>.</returns>
+        IGaugeDoubleBuilder GetGaugeDoubleBuilder(string name);
+
+        /// <summary>
+        /// Gets the builder for <see cref="IGaugeLong"/>.
+        /// </summary>
+        /// <param name="name">Name of the counter.</param>
+        /// <returns>The builder for the <see cref="IGaugeLong"/>.</returns>
+        IGaugeLongBuilder GetGaugeLongBuilder(string name);
+
+        /// <summary>
+        /// Gets the builder for the <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="name">The name of the <see cref="IMeasure"/>.</param>
+        /// <returns>The <see cref="IMeasureBuilder"/> to build the <see cref="IMeasure"/>.</returns>
+        IMeasureBuilder GetMeasureBuilder(string name);
+
+        void Record(IEnumerable<IMeasurement> measurements);
+
+        void Record(IEnumerable<IMeasurement> measurements, ITagContext tagContext);
+
+        void Record(IEnumerable<IMeasurement> measurements, ITagContext tagContext, SpanContext spanContext);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/IMetric{T}.cs b/src/OpenTelemetry.Abstractions/Metrics/IMetric{T}.cs
new file mode 100644
index 00000000000..c461fd8e3f5
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/IMetric{T}.cs
@@ -0,0 +1,72 @@
+// <copyright file="IMetric{T}.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    using System;
+    using System.Collections.Generic;
+    using OpenTelemetry.Resources;
+
+    /// <summary>
+    /// Base interface for all metrics defined in this package.
+    /// </summary>
+    /// <typeparam name="T">Type of the time series of the metric.</typeparam>
+    public interface IMetric<T>
+    {
+        /// <summary>
+        /// Creates a time series and returns a time series if the specified labelValues
+        /// is not already associated with this metric, else returns an existing time series.
+        ///
+        /// It is recommended to keep a reference to the time series instead of always calling this
+        /// method for every operations.
+        /// </summary>
+        /// <param name="labelValues">
+        /// The list of label values. The number of label values must be the same to
+        /// that of the label keys passed to.
+        /// </param>
+        /// <returns>A time series the value of single metric.</returns>
+        T GetOrCreateTimeSeries(IEnumerable<string> labelValues);
+
+        /// <summary>
+        /// Returns a time series for a metric with all labels not set (default label values).
+        /// </summary>
+        /// <returns>A time series for a metric with all labels not set (default label values)</returns>
+        T GetDefaultTimeSeries();
+
+        /// <summary>
+        /// Sets a callback that gets executed every time before exporting this metric. Used to
+        /// implement pull-based metric.
+        ///
+        /// Evaluation is deferred until needed, if this <see cref="IMetric{T}"/> is not exported then it will never be called.
+        /// </summary>
+        /// <param name="metricUpdater">The callback to be executed before export.</param>
+        void SetCallback(Action metricUpdater);
+
+        /// <summary>
+        /// Removes the time series from the metric, if it is present. i.e. references to previous time series
+        /// are invalid (not part of the metric).
+        ///
+        /// If value is missing for one of the predefined keys null must be used for that value.
+        /// </summary>
+        /// <param name="labelValues">The list of label values</param>
+        void RemoveTimeSeries(IEnumerable<string> labelValues);
+
+        /// <summary>
+        /// Removes all time series from the metric. i.e. references to all previous time series are invalid (not part of the metric).
+        /// </summary>
+        void Clear();
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleBuilder.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleBuilder.cs
new file mode 100644
index 00000000000..e5c935cbd8b
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleBuilder.cs
@@ -0,0 +1,25 @@
+// <copyright file="ICounterDoubleBuilder.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// The builder for the <see cref="ICounterDouble"/>.
+    /// </summary>
+    public interface ICounterDoubleBuilder : IMetricBuilder<ICounterDoubleTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleTimeSeries.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleTimeSeries.cs
new file mode 100644
index 00000000000..31e33658c1a
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterDoubleTimeSeries.cs
@@ -0,0 +1,28 @@
+// <copyright file="ICounterDoubleTimeSeries.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// Time series type for <see cref="ICounterDouble"/>.
+    /// </summary>
+    public interface ICounterDoubleTimeSeries
+    {
+        void Add(double delta);
+
+        void Set(double val);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongBuilder.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongBuilder.cs
new file mode 100644
index 00000000000..3b37e488422
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongBuilder.cs
@@ -0,0 +1,25 @@
+// <copyright file="ICounterLongBuilder.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// The builder for the <see cref="ICounterLong"/>.
+    /// </summary>
+    public interface ICounterLongBuilder : IMetricBuilder<ICounterLongTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongTimeSeries.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongTimeSeries.cs
new file mode 100644
index 00000000000..0200ebd08db
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/ICounterLongTimeSeries.cs
@@ -0,0 +1,28 @@
+// <copyright file="ICounterLongTimeSeries.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// Time series type for <see cref="ICounterDouble"/>.
+    /// </summary>
+    public interface ICounterLongTimeSeries
+    {
+        void Add(long delta);
+
+        void Set(long val);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleBuilder.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleBuilder.cs
new file mode 100644
index 00000000000..97abcdffdb0
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleBuilder.cs
@@ -0,0 +1,25 @@
+// <copyright file="IGaugeDoubleBuilder.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// The builder for the <see cref="IGaugeDouble"/>.
+    /// </summary>
+    public interface IGaugeDoubleBuilder : IMetricBuilder<IGaugeDoubleTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleTimeSeries.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleTimeSeries.cs
new file mode 100644
index 00000000000..d2b44a6917d
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeDoubleTimeSeries.cs
@@ -0,0 +1,28 @@
+// <copyright file="IGaugeDoubleTimeSeries.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// Time series type for <see cref="IGaugeDouble"/>.
+    /// </summary>
+    public interface IGaugeDoubleTimeSeries
+    {
+        void Add(double delta);
+
+        void Set(double val);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongBuilder.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongBuilder.cs
new file mode 100644
index 00000000000..54c31a1e288
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongBuilder.cs
@@ -0,0 +1,25 @@
+// <copyright file="IGaugeLongBuilder.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// The builder for the <see cref="IGaugeLong"/>.
+    /// </summary>
+    public interface IGaugeLongBuilder : IMetricBuilder<IGaugeLongTimeSeries>
+    {
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongTimeSeries.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongTimeSeries.cs
new file mode 100644
index 00000000000..1fb581ca384
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IGaugeLongTimeSeries.cs
@@ -0,0 +1,28 @@
+// <copyright file="IGaugeLongTimeSeries.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    /// <summary>
+    /// Time series type for <see cref="IGaugeLong"/>.
+    /// </summary>
+    public interface IGaugeLongTimeSeries
+    {
+        void Add(long delta);
+
+        void Set(long val);
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMeasureBuilder.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMeasureBuilder.cs
new file mode 100644
index 00000000000..65d828c48d1
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMeasureBuilder.cs
@@ -0,0 +1,53 @@
+// <copyright file="IMeasureBuilder.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    using System;
+
+    /// <summary>
+    /// Builder for the <see cref="IMeasure"/>.
+    /// </summary>
+    public interface IMeasureBuilder
+    {
+        /// <summary>
+        /// Sets the description of the <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="description">The detailed description of the <see cref="IMeasure"/>.</param>
+        /// <returns>This builder object.</returns>
+        IMeasureBuilder SetDescription(string description);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="unit">The detailed description of the <see cref="IMeasure"/>.</param>
+        /// <returns>This builder object.</returns>
+        IMeasureBuilder SetUnit(string unit);
+
+        /// <summary>
+        /// Sets the corresponding to the underlying value of the <see cref="IMeasure"/>.
+        /// </summary>
+        /// <param name="type">The detailed description of the <see cref="IMeasure"/>.</param>
+        /// <returns>This builder object.</returns>
+        IMeasureBuilder SetType(MeasureType type);
+
+        /// <summary>
+        /// Builds the <see cref="IMeasure"/>.
+        /// </summary>
+        /// <returns>The <see cref="IMeasure"/> object.</returns>
+        IMeasure Build();
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMetricBuilder{T}.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMetricBuilder{T}.cs
new file mode 100644
index 00000000000..7a7ef777c0e
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/IMetricBuilder{T}.cs
@@ -0,0 +1,76 @@
+// <copyright file="IMetricBuilder{T}.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    using System.Collections.Generic;
+    using OpenTelemetry.Resources;
+
+    /// <summary>
+    /// Metric builder interface.
+    /// </summary>
+    /// <typeparam name="T">Type of time series in metric.</typeparam>
+    public interface IMetricBuilder<T>
+    {
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="description">Description of the metric.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetDescription(string description);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="unit">Unit of the metric.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetUnit(string unit);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="labelKeys">List of keys for dynamic labels.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetLabelKeys(IEnumerable<LabelKey> labelKeys);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="constantLabels">Set of labels with values.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetConstantLabels(IDictionary<LabelKey, string> constantLabels);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="component">Component reporting this metric.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetComponent(string component);
+
+        /// <summary>
+        /// Sets the description of the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <param name="resource">Resource associated with the metric.</param>
+        /// <returns>This builder instance.</returns>
+        IMetricBuilder<T> SetResource(Resource resource);
+
+        /// <summary>
+        /// Builds the <see cref="IMetric{T}"/>.
+        /// </summary>
+        /// <returns>The new instance of <see cref="IMetric{T}"/>.</returns>
+        IMetric<T> Build();
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/Implementation/MeasureType.cs b/src/OpenTelemetry.Abstractions/Metrics/Implementation/MeasureType.cs
new file mode 100644
index 00000000000..d00e65bd07b
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/Implementation/MeasureType.cs
@@ -0,0 +1,31 @@
+// <copyright file="MeasureType.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics.Implementation
+{
+    public enum MeasureType
+    {
+        /// <summary>
+        /// Long type values.
+        /// </summary>
+        Long,
+
+        /// <summary>
+        /// Double type values.
+        /// </summary>
+        Double,
+    }
+}
diff --git a/src/OpenTelemetry.Abstractions/Metrics/LabelKey.cs b/src/OpenTelemetry.Abstractions/Metrics/LabelKey.cs
new file mode 100644
index 00000000000..fc9014e7dfa
--- /dev/null
+++ b/src/OpenTelemetry.Abstractions/Metrics/LabelKey.cs
@@ -0,0 +1,53 @@
+// <copyright file="LabelKey.cs" company="OpenTelemetry Authors">
+// Copyright 2018, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+namespace OpenTelemetry.Metrics
+{
+    /// <summary>
+    /// The key of a label associated with a <see cref="IMetric{T}"/>.
+    /// </summary>
+    public sealed class LabelKey
+    {
+        private LabelKey()
+        {
+        }
+
+        /// <summary>
+        /// Gets a key of the label.
+        /// </summary>
+        public string Key { get; private set; }
+
+        /// <summary>
+        /// Gets a human-readable description of what this label key represents.
+        /// </summary>
+        public string Description { get; private set; }
+
+        /// <summary>
+        /// Creates a new instance of a <see cref="LabelKey"/>.
+        /// </summary>
+        /// <param name="key">The key of the label.</param>
+        /// <param name="description">A human-readable description of what this label key represents.</param>
+        /// <returns>A new instance of <see cref="LabelKey"/>.</returns>
+        public static LabelKey Create(string key, string description)
+        {
+            return new LabelKey()
+            {
+                Key = key,
+                Description = description,
+            };
+        }
+    }
+}