After departing from Apple in the mid-80's, Steve Jobs (Apple's iCEO) formed NeXT, the epitome of visionary thinking and development, which created the NeXTSTEP operating system (using the Mach kernel), upon which Rhapsody, MacOS Server, and MacOS X are based. They also used to make MC680x0-based hardware, which was quite swift and posessing of excellent industrial design, on which to run this OS. Here are photos of the two main machine form-factors that came out of NeXT (excuse the small images). It's good to know where you're coming from.

Source : http://www.blakespot.com/mac/