An operating system (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 line or a graphical user interface (GUI).

Basic function of OS:

Every computer requires an operating system to function, no matter the make, model or age. While the most obvious function of an operating system is to provide you with an interface with which to work, it controls many other elements behind the scenes as well. The operating system enables the interaction of a computer's hardware and software. Without it, the computer would be an expensive paperweight.

Hardware Management

One of the most important functions of an operating system is the management of all the computer's internal and external hardware. The operating system controls all connected devices, telling them how to operate and interact. The results of said operations and interactions are the basic performance of the computer. Some examples of the hardware that the operating system controls include the hard disk, optical drives, video cards and external port controllers, such as USB and Fire wire.

Program Control

Operating systems also run programs, enabling them to operate and function as designed. Programs have to be designed to run with a particular operating system in order to function, as the operating system needs to display any interfaces and facilitate communications among the programs and your computer's connected hardware. Without the operating system to run it, programs can't perform their tasks.

Data Access

The operating system is also in charge of accessing, storing and retrieving data on the computer's hard drive. It also manages data stored temporarily in the computer's RAM memory. The data stored and retrieved can include document files, picture data, videos and music. While the hard drive itself reads and writes the data, the operating system tells it what to write and how to read it.

System Resource Management

The operating system manages a computer's resources, allocating them as needed. Which tasks the CPU processes in what order, which functions or programs are assigned processing power or memory first, and many other important resource allocation tasks are controlled by the operating system. Crucial operations are given priority based on presets inside the operating system that determine the importance of a process or program.

Network Communication

The operating system also facilitates network communication by enabling connected network devices to communicate with the computer and with any programs that require them. Network cards, such as Ethernet ports and wireless LAN cards, have the tools to connect with networks but need the operating system to direct their communication correctly so information can be exchanged. The operating system also interprets the information that comes in and determines which installed program can best display it for you.