The Secure Sockets Layer (SSL) is a high level and commonly-used security protocol for protecting the confidentiality and security of a message transmission on the Internet. SSL is more commonly used by most commerce servers on the World Wide Web for secure transactions. SSL is an open protocol that has been submitted to several industry groups as the industry security standard and it is denoted by the letters https:// in the URL. Based on RSA Data Security’s public-key cryptography, SSL uses a program layer located between the Internet’s Hypertext Transfer Protocol (HTTP) and Transport Control Protocol (TCP) layers. The “sockets” part of the term refers to the sockets method of passing data back and forth between a client and a server program in a network or between program layers in the same computer.
SSL has more recently became known as Transport Layer Security, or TLS for short.