is a protocol that allows clients and servers to authenticate each other. After establishing a connection with a server, a client sends a hello message to the server that it wants to communicate with. The server responds with a hello message that also instructs the client on the protocol in use, the encryption method, a session identifier, and the compression method in use, if any. The sever then provides its digital signature (certificate) and requests one from the client.
SSL (Secure Sockets Layer)