HTTPS
Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP) for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS), or, formerly, its predecessor, Secure Sockets Layer (SSL). The protocol is therefore also often referred to as HTTP over TLS, or HTTP over SSL.
Secure Hypertext Transfer Protocol
Web browsers typically use HTTP to communicate with web servers, sending and receiving information without encrypting it. For sensitive transactions, such as Internet e-commerce or online access to financial accounts, the browser and server must encrypt this information.
HTTPS and S-HTTP were both defined in the mid-1990s to address this need. S-HTTP was used by Spyglass's web server, while Netscape and Microsoft supported HTTPS rather than S-HTTP, leading to HTTPS becoming the "de facto" standard mechanism for securing web communications.