https://web.archive.org/web/20131219003849/http://www.winamp...

> What happened to Winamp 4? You're not imagining things. Yes, we skipped a version number for the following reasons: a) Winamp 5 combines the best aspects of Winamp 2 and Winamp 3 into one player. Hence Winamp 2 + Winamp 3 = Winamp 5! b) Who the hell wants to see a Winamp 4 Skin :P c) We think that a Fibonacci sequence for versioning might be pretty damn cool. d)We improved so much in Winamp 5 that we figured it warranted skipping a version. ;)