A protocol developed by Netscape for secure transmission of Web content over the Internet. HTTPS is another name for Netscape’s implementation of the Secure Sockets Layer (SSL) protocol that functions as a subprotocol to the application layer (layer 7) protocol, Hypertext Transfer Protocol (HTTP).
HTTPS is based on the public key cryptography system and allows information transmitted over the Internet to be encrypted for greater security. To run HTTPS on a Web server, you must install a digital certificate on the server. Web browsers will then connect to the server by providing a Uniform Resource Locator (URL) that begins with the prefix https:// rather than http://. The designation “HTTPS” comes from the combination of HTTP and secure.
HTTPS uses the TCP well-known port number 443 instead of port 80, which is used by HTTP. HTTPS is not the same as Secure Hypertext Transfer Protocol (S-HTTP).