Definition

operating system (OS)

Part of the Operating systems glossary:

What is an operating system? 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:

  • 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.
  • It manages the sharing of internal memory among multiple applications.
  • It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
  • 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.
  • It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
  • 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, VMS, OS/400, AIX, and z/OS are all examples of operating systems.

This was last updated in June 2014
Posted by: Margaret Rouse

Related Terms

Definitions

  • Microsoft Windows Recovery Environment (Windows RE)

    - The Microsoft Windows Recovery Environment, or Windows RE, is a simplified, scaled-back version of the Windows operating system that is used to boot the system when Windows 8.x, Windows Server 2012... (SearchEnterpriseDesktop.com)

  • BIOS (basic input/output system)

    - BIOS (basic input/output system) is the program a personal computer's microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer's o... (WhatIs.com)

  • TailsOS

    - TailsOS is a LiveDistro-based operating system that is configured to run from removable storage and to leave no information stored on the computer after the user’s session. A LiveDistro is a distr... (WhatIs.com)

Glossaries

  • Operating systems

    - Terms related to operating systems, including definitions about open source and proprietary operating systems and words and phrases about system programs, boot mechanisms, kernels, command interpre...

  • Internet applications

    - This WhatIs.com glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by ITKnowledgeExchange.com

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment

Share
Comments

    Results

    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.