docs: add protocol concepts doc (#1013)

Co-authored-by: Alejandra Quetzalli <[email protected]>

pages/docs/concepts/protocol.md

@@ -0,0 +1,45 @@
+---
+title: Protocol
+weight: 25
+---
+
+
+## What is a protocol?
+A protocol is a set of rules that specifies how information is exchanged between applications and/or servers.
+
+Protocol examples:
+* [WebSockets](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket)
+* [HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
+* [Kafka](https://kafka.apache.org/)
+* [MQTT](https://mqtt.org/)
+
+## Why do we need protocols?
+Whenever a producer detects a state change (events) and publishes those events as messages, a protocol carries those messages to the channel and then to a consumer. Protocol plays a vital role in message transmission.
+
+```mermaid
+sequenceDiagram
+    Publisher->>+Broker: PUBLISH(QoS0,Msg)
+    Broker->>+Subscriber: PUBLISH(QoS0,Msg)
+    Publisher->>+Publisher: Delete(Msg)
+```
+
+The diagram above depicts the message exchange flow from `producer` to `broker` to `consumer` using the MQTT protocol with QoS0 (quality of service 0). This means that information exchanged from `producer` to `broker` to `consumer` is delivered at most once.
+
+The quality of service information rule is specified on a protocol level. Broker implementations and other involved actors must act accordingly.
+
+In AsyncAPI documents, all protocol-specific details that the application follows can be described using [bindings](/docs/reference/specification/v2.5.0#definitionsBindings).
+
+<DocsButton
+ suggestions={[
+    {
+      href:'/docs/concepts/application',
+      type: 'back',  
+      title: 'Application',
+   },
+   {
+      href:'/docs/tutorials',
+      type: 'next',  
+      title: 'Tutorials - Overview',
+   }
+ ]}
+/>