Original Link: http://www.imore.com/os-x-evolution-road-mavericks

Peter Cohen:

It was a long road to OS X 10.9 Mavericks. Mac OS X was first introduced as a public beta (codenamed Kodiak) in September of 2000, and beta it was – a radical departure from Mac OS 9, both in look (introducing the “Aqua” interface) and in operation. Mac OS X was built on a UNIX foundation, and was more closely related to the NextStep operating system that had been developed by NeXT, the computing company Steve Jobs founded between stints running Apple.