Through the second half of the 1980s, the company built market share only to see it dissipate in the 1990s as the personal computer market shifted towards IBM PC compatible machines running MS-DOS and Microsoft Windows. Apple consolidated multiple consumer-level desktop models into the 1998 iMac all-in-one, which was a sales success and saw the Macintosh brand revitalized. Current Mac systems are mainly targeted at the home, education, and creative professional markets. They are: the aforementioned (though upgraded) iMac and the entry-level Mac mini desktop models, the workstation-level Mac Pro tower, the MacBook, MacBook Air and MacBook Pro laptops, and the Xserve server.
Production of the Mac is based on a vertical integration model in that Apple facilitates all aspects of its hardware and creates its own operating system that is pre-installed on all Mac computers. This is in contrast to most IBM PC compatibles, where multiple sellers create hardware intended to run another company's software. Apple exclusively produces Mac hardware, choosing internal systems, designs, and prices. Apple does use third party components, however; current Macintosh CPUs use Intel's x86 architecture. Previous models used the AIM alliance's PowerPC and early models used Motorola's 68k. Apple also develops the operating system for the Mac, currently Mac OS X 10.5 "Leopard". The modern Mac, like other personal computers, is capable of running alternative operating systems such as Linux, FreeBSD, and Microsoft Windows, though other computers cannot normally run Mac OS X.
An article from http://en.wikipedia.org/wiki/Macintosh