This article explains why IPv5 never became an official Internet protocol.

An Internet Protocol is the set of rules that govern how information packets are sent over a network. IPv5 is a version of the Internet Protocol (IP) that was never formally adopted as a standard. The "v5" stands for version 5 of the Internet Protocol. Computer networks use version 4, usually called IPv4, or a later version: IPv6.

IPv5 never became an official protocol due to a number of limitations. What is known as IPv5 started out under a different name: ​Internet Stream Protocol, or ST for short.

The ST/IPv5 Internet Protocol was a way to stream video and voice data that Apple, NeXT, and Sun Microsystems developed, and it was experimental. ST was effective at transferring data packets on specific frequencies while maintaining communication.