Transport Layer Security - Definition from the Hotspot Shield Glossary
Transport Layer Security is a protocol that is primarily involved with data integrity for network communication. TLS is used to guarantee privacy and integrity of the data transferred between client/server applications that communicated over the internet.
The protocol is split into two separate layers - The TLS Record Protocol and the TLS Handshake Protocol. The record protocol ensures that a private and reliable connection is established using data encryption. The handshake protocol provides a means of authentication between the client and the server, and the encryption type and key that will be used to encrypt the data. These two protocols happen before any data is transferred between the server and client. TLS is an extension of SSL (Secure Socket Layer) and is based on the original 3.0 version created by Netscape.