Operating system is basically a system program which is a medium between all the computer hardware components and the application softwares.
Through operating system, user/programmer can use their application program to communicate with computer components to perform their required computing tasks.
Without an operating system, application programs and computer hardware is nothing and users can't do anything their computing tasks.
Operating systems perform the following two functions:
The operating system's function is to present the user with the equivalent of an extended or virtual machine, that is easier to program than the underlying hardware.
Operating system basically provides a variety of services that programs can obtain using special instructions called system calls.
Let's imagine that three programs present on some computers. All tied to print their output simultaneously on the same printer. Then the first few lines might be from the first program, second program, or third program and the next few lines might also be from the first program, second program, or the third program and so on.
In this way, the printout result of all the three programs would be chaos. Therefore, here in this case operating system can bring order by buffering all the output destined for the printer on the disk. When one program is finished, then operating system copy its output from the disk file where it has been stored to the printer, while at the same time the other program can continue generating more output.
In this manner, operating system can perform for all the programs to print their actual output in a correct way.
Here are the list of some popular windows based personal computer operating systems:
And the following are the list of some popular linux based operating system, mostly used by advance computer user: