feat: content routing overview

content/concepts/content-routing/overview.md

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-Coming soon!
+## Overview
+
+Content routing refers to the process of directing data to its intended recipient within a
+P2P network. In a traditional client-server network, routing is a straightforward process
+because a central authority manages the flow of data. However, in a P2P network, there is
+no central authority, so routing becomes more complex.
+
+One of the main challenges of content routing in P2P networks is scalability. As the number
+of peers in a network increases, the number of possible routes for data to travel also increases.
+This can lead to a situation where the routing table becomes excessively large and difficult to
+manage.
+
+Another challenge is fault tolerance. In a centralized network, if the central server goes down,
+the entire network goes down. In a P2P network, if a peer goes down, the network can still
+function, but losing that peer can create a bottleneck and make routing more difficult.
+
+In general, specific characteristics of P2P networks complicate this process, including:
+
+- The lack of universal orchestration that a central server can provide when
+  querying and retrieving content.
+- Not having a central directory that contains information about reaching every peer
+  in the network.
+- The presence of high node churn.
+- Creating a resilient, scalable, and optimal routing protocol that is resistant to
+- Resistance against Sybil attacks.
+- Forward compatibility.
+
+## Content Routing in libp2p
+
+libp2p provides a set of modules for different network-level functionality, including
+a content routing interface.
+
+```shell
+interface ContentRouting {
+ Provide(CID, bool) error
+ FindProviders(CID) [Multiaddr]
+}
+```
+
+In libp2p, content routing is based on a
+[Distributed Hash Table (DHT) called Kademlia](../introduction/protocols/kaddht.md). Kademlia assigns
+each piece of content a unique identifier and stores the content on the peer whose identifier is
+closest to the content's identifier. This allows for efficient routing, reducing the number of possible
+routes. The content router is simply an index of the peer serving the content of interest,
+and a DHT is used to maintain a P2P index. More information can be found in the
+[Kad-DHT content routing document](kaddht.md).
+
+{{< alert icon="" context="note">}}
+While there are different design approaches for a content routing protocol, such as
+Kademlia DHT, DNS, and BitTorrent trackers, the libp2p
+documentation will focus on a DHT-based approach that implements the content routing
+interface: Kad-DHT-libp2p.
+{{< /alert >}}