US-CERT Cyber Security Tip ST04-021 -- Understanding Your Computer: Operating Systems

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                      Cyber Security Tip ST04-021
              Understanding Your Computer: Operating Systems

   The operating system is the most fundamental program that runs on your
   computer. It serves as the basis for how everything else works.

What is an operating system?

   An  operating  system  (OS)  is  the  main  program  on a computer. It
   performs a variety of functions, including
     * determining what types of software you can install
     * coordinating the applications running on the computer at any given
       time
     * making  sure that individual pieces of hardware, such as printers,
       keyboards, and disk drives, all communicate properly
     * allowing  applications such as word processors, email clients, and
       web browsers to perform tasks on the system (e.g., drawing windows
       on  the  screen,  opening  files,  communicating on a network) and
       utilize other system resources (e.g., printers, disk drives)
     * reporting error messages

   The OS also determines how you see information and perform tasks. Some
   operating systems use a graphical user interface (GUI), which presents
   information  through  pictures (icons, buttons, dialog boxes, etc.) as
   well as words. Other operating systems can rely solely on text.

How do you choose an operating system?

   In  very  simplistic terms, when you choose to buy a computer, you are
   usually also choosing an operating system. Although you may change it,
   vendors  typically  ship computers with a particular operating system.
   There are multiple operating systems, each with different features and
   benefits, but the following three are the most common:
     * Windows  -  Windows,  with  versions including Windows Me, Windows
       2000, and Windows XP, is the most common operating system for home
       users.  It  is  produced by Microsoft and is typically included on
       machines  purchased  in electronics stores or from vendors such as
       Dell  or Gateway. The Windows OS uses a GUI, which many users find
       more appealing and easier to use than text-based interfaces.
     * Mac  OS  X  -  Produced by Apple, Mac OS X is the operating system
       used  on  Macintosh  computers.  With the exception of a different
       GUI,  it  is  similar  to  the  Windows  interface  in  the way it
       operates.
     * Linux  and  other UNIX-derived operating systems - Linux and other
       systems derived from the UNIX operating system are frequently used
       for  specialized  workstations  and servers, such as web and email
       servers.  Because  they are often more difficult for general users
       or  require  specialized knowledge and skills to operate, they are
       not  very  popular  with  home users. However, as they continue to
       develop  and become easier to use, they may become more popular on
       typical home user systems.
     _________________________________________________________________

    Authors: Mindi McDowell, Chad Dougherty
     _________________________________________________________________

    Produced 2004 by US-CERT, a government organization.

    Note: This tip was previously published and is being re-distributed 
    to increase awareness. 
  
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