I never heard about IPv5, what gives?

I am looking for IPv5. Where is it?

Gone hiding. IPv5 was developed in the late 1970'th. It never left the 'experimental' stage. At one time or another, IPv5 was also called 'Internet Streaming Protocol,' or ST, or ST/IPv5; yes, you guessed it correctly, it was supposed to handle all these new streaming sound and streaming video messages. ST never got off the ground.
But, 10-15 years later on, her and there, an improved protocol ST2, or ST+ was implemented by vendors like IBM, NeXT, Apple, Sun. Each implementation was a bit different, and again, it died.

Fast forward to 1994. IPng, IP next generation, started to emerge. Since the "5" was taken, used or not, the new protocol became IPv6.