SSL stands for secure sockets layer, a technology used on the Internet to transmit online communications in an encrypted form. A digitally secure communications channel is established between the server (Web site) and the client (your computer and Web browser), after which all data passed between the two is encrypted. The encryption and decryption process is provided by the use of digital signatures, and determining whether a Web site is what it says it is can be ascertained by using digital certificates that are signed by a Certificate Authority acting as a trusted third party.