Write short notes on the following:

Multi-user operating system

Multi-user operating system allows more than one user to use the same computer at the same time or at different times. Some Operating Systems, which fall in this category are: Windows 2000, Windows NT, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, Linux, Unix. Windows 2000 was the first version of Windows, which allowed creation of several user accounts on a single machine.