diff --git a/relay/doc.go b/relay/doc.go
index 09d034edd..d0306204a 100644
--- a/relay/doc.go
+++ b/relay/doc.go
@@ -4,5 +4,11 @@ The `relay` package contains the implementation of the Relay server and client.
 messages between peers on a single network channel. In this implementation the transport layer is the WebSocket
 protocol.
 
+Between the server and client communication has been design a custom protocol and message format. These messages are
+transported over the WebSocket connection. Optionally the server can use TLS to secure the communication.
+
+The service can support multiple Relay server instances. For this purpose the peers must know the server instance URL.
+This URL will be sent to the target peer to choose the common Relay server for the communication via Signal service.
+
 */
 package relay