A popular security protocol that ensures privacy between servers (applications) and clients (users) communicating on the IP network. When a server and client communicate, TLS ensures that no third party may eavesdrop or tamper with any message. TLS is the successor to the Secure Sockets Layer (SSL).

TLS is composed of two layers: the TLS Record Protocol and the TLS Handshake Protocol. The TLS Record Protocol provides connection security using some encryption method such as the Data Encryption Standard (DES), but can also be used without encryption. The TLS Handshake Protocol allows the server and client to authenticate each other and to negotiate an encryption algorithm and cryptographic keys before data is exchanged.

Although TLS is based on Netscape's SSL 3.0 protocol, the two are not interoperable. See Secure Sockets Layer (SSL).