The PowerPC is a RISC processor developed in a collaborative effort between IBM, Apple, and Motorola. It is currently produced by a few different companies, of course including its original developers. A few different OSes run on PowerPC based machines, including Mac OS, AIX, Solaris, Windows NT, Linux, Mac OS X, BeOS, and AmigaOS. At any given time, the fastest processor in the world is usually either a PowerPC or an Alpha, but sometimes SPARCs and PA-RISCs make the list, too.