macOS is a direct descendant of NeXTSTEPOpenStep → Rhapsody → Mac OS X Server 1.0 → Mac OS X Public Beta → Mac OS X 10.0 → ...Up until Mac OS X 10.4 Tiger, traces of NeXTSTEP icons were still present Internal HistorymacOS InternalsmacOS Internals · GitHubhttps://gist.github.com/kconner/cff08fe3e0bb857ea33b47d965b3e19fnamu.wikihttps://namu.wiki/w/macOS#s-2.2