Close this search box.

What is an operating system?



An operating system is a special piece of software that manages the general operation of a computer system:

  • It provides a user interface so that we can interact with the computer

  • It manages applications that are running on the computer, starting them when the user requests and stopping them when they are no longer needed

  • It manages files, helping us save our work, organize our files, find files that we have saved, and load files

  • It manages the memory of the computer, deciding what should be loaded into memory and what should be removed

  • It looks after computer security, preventing unauthorized access to the system

  • It manages the computer’s input and output hardware such as printers, etc.


A computer is useless without an operating system.


However, simply having an operating system running on a computer is not very useful; we need application software (such as Word, Excel, and so on) to actually do useful tasks with the computer.


Some operating systems you may have heard of are: 

  • Windows XP

  • Windows Vista

  • Mac OS X

  • Linux

User Interfaces 

The user interface is the system that people use to interact with computers (to give them commands, see the results of those commands, and so on).


There are two you should be aware of:

GUI stands for Graphical User Interface (GUI)

CLI stands for Command-Line Interface (CLI)


Graphical User Interface 

A graphical user interface (GUI) is a user interface that is based on visual (graphical) elements:

  • Windows are screen areas that display information.

  • Icons are small images that are used to represent folders, software, and other items.

  • Menus are lists of options from which the user can choose.

  • A pointer is an arrow that can be moved around the screen to select items.


Windows XP is an example of a graphical user interface (GUI) operating system.


Because of the visual nature of the interface, Stacks Image 921 GUIs are quite simple to use – the user has plenty of visual cues as to what things do.


However, in order to display all of the nice graphics required by a GUI, a powerful computer is required.


Command Line Interface 


Many years ago, when computers were not very powerful, the colorful graphics required for a GUI could not be displayed. The ‘command line’ was the only interface available to most computer users.


The user would only see a black screen. To make anything happen, they would have to type a command.


For example, to copy a text file called NOTES from a floppy disc to a hard drive, the user would type:






To use the computer system, the user would have to learn a whole new set of strange commands. Furthermore, there were no visual cues to tell you what to do next, which made it unappealing to look at.


Because computers were once quite difficult to use, this type of interface is really only suitable for expert users.


Views: 141