Operating System: An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Types of Operating Systems: 1. Single Task & Multi Tasking Systems: A single-tasking system can only run one program at a time, while a multi tasking operating system allows more than one program to be running concurrently. Single Task Functions like printing a document, downloading images, etc., can be performed only one at a time. Examples include MS-DOS, Palm OS, etc. Multi Tasking Operating Systems Examples include Microsoft Windows and Macintosh OS. 2. Multiuser/Multitasking OS It is an operating system that permits several users to utilize the programs that are concurrently running on a single network server. The single network server is termed as "Terminal server". "Terminal client" is a software that supports user sessions. Examples include UNIX, MVS, etc. 3. Distributed Operaing Syste