An Operating System is usually an essential component of your computer.
An operating system or OS
, is piece of software that enables the computer's hardware to communicate and operate with applications. Without an OS, many applications could not run.
Applications are written to run on top of a particular operating system. Your choice of operating system determines to a great extent the applications you can run. Multitasking refers to the running of multiple independent computer programs on the same computer; giving the appearance that it is performing the tasks at the same time.
Most new computers can manage hundred of tasks simultaneously. The computer's processor and memory are the main determinants of how many tasks can be handled. Management of these tasks generally done via time-sharing, which means that each program uses a share of the computer's resources to execute. The OS manages all of this without any help from the computer user.
Since the operating system determines what software is available for a given computer, many users observe the high volume of software available for Windows machines and make their computer purchases accordingly. Other well known operating systems include Mac OS X, several varieties of Linux (the most popular being Ubuntu), FreeBSD and Solaris. Mac, Linux, FreeBSD and Solaris are all built on top of Unix