Operating System

From Wikipedia, the free encyclopedia

An operating system{OS} is a set of computer programs that manage the hardware
and software resources of a computer. An operating system processes raw system
and user input and responds by allocating and managing tasks and internal
system resources as a service to users and programs of the system. At the
foundation of all system software, an operating system performs basic tasks
such as controlling and allocating memory, prioritizing system requests,
controlling input and output devices, facilitating networking and managing file
systems. Most operating systems come with an application that provides an
interface to the OS managed resources. These applications have had command
line interpreters as a basic user interface but, since the mid-1980s, have
been implemented as a graphical user interface (GUI) for ease of operation.
Operating Systems themselves have no user interfaces; the user of an OS is
an application, not a person. The operating system forms a platform for other
system software and for application software. Windows, Linux, and Mac OS are
some of the most popular OSes.

From TechTarget: 

 - An operating system (sometimes abbreviated as "OS") is the program that, after being
initially loaded into the computer by a boot program, manages all the other programs in
a computer. The other programs are called applications or application programs. The
application programs make use of the operating system by making requests for services
through a defined application program interface (API). In addition, users can interact
directly with the operating system through a user interface such as a command language
or a graphical user interface (GUI).

An operating system performs these services for applications:

1.  In a multitasking operating system where multiple programs can be running at the same 
time, the operating system determines which applications should run in what order and how 
much time should be allowed for each application before giving another application a turn.
2.  It manages the sharing of internal memory among multiple applications.
3.  It handles input and output to and from attached hardware devices, such as hard disks,
printers, and dial-up ports.
4.  It sends messages to each application or interactive user (or to a system operator) about
the status of operation and any errors that may have occurred.
5.  It can offload the management of what are called batch jobs (for example, printing) so that
the initiating application is freed from this work.
6.  On computers that can provide parallel processing, an operating system can manage how
to divide the program so that it runs on more than one processor at a time.

All major computer platforms (hardware and software) require and sometimes include an
operating system. Linux, Windows Vista, Windows 7, are all examples of operating systems.