The Macintosh operating system from Apple Computer has been around since 1984, and was the first operating system to introduce the graphical user interface (GUI). Since then, it has been overtaken by Windows, even though Mac users are quick to defend it and say that the Mac OS is superior to Windows in every way. While this may be true, the Macintosh lost market share due to a number of factors, the primary one being that Apple insisted that it supply all the hardware and software for the Mac. Windows, on the other hand was available on any PC that supported the IBM PC standard. A combination of factors helped Microsoft gain market share while the Mac OS languished. Of late, there has been renewed interest in the Mac; more and more people have begun buying Macs again. In March 2001, Apple introduced a new version of the Mac called Mac OS X (pronounced Mac OS ten). This was a complete rewrite of the entire Macintosh operating system and based on the UNIX operating system core.