What is an endpoint?

In SQL Server 2005, a connection between servers is managed through an endpoint. The endpoint is an object in SQL Server 2005 through which SQL Server computers communicate with each other over the network. For database mirroring, a SQL Server computer requires a dedicated database mirroring endpoint. The database mirroring endpoint is used to communicate between the servers. It uses the TCP protocol to send and receive messages between the servers in the database mirroring sessions. Each endpoint listens on a unique TCP port number. Clients do not use the database mirroring endpoint to connect to the principal server.