MS-DOS which stands for Microsoft Disk Operating System was purchased by Bill Gates from a small company; he then refined it and sold it to IBM to be used by them as the standard operating system on the Personal Computer in 1981. MS-DOS is a command line operating system, which means you must type in commands for the things you want the computer to do. The syntax (the way you enter the commands) must be correct or you get some obscure error message like: bad command or file name. Needless to say, this created irritation and frustration for people just learning the computer and some people gave up in disgust. For the people who persevered and learned how to work effectively in DOS, working in this operating system can be elegant and fast. Of course, this meant they had to memorize many commands or look them up every time they were used.