User interface: is a system that allow the user to interact (command) with the computer.
There are 2 types of the user interface:

• Graphical user interface (GUI)
• Command line interface (CLI)

Graphical user interface (GUI)

GUI is quite easy to use due to the visual nature interface, but this type of user interface use up a lot of power, so the computer must be quite powerful.

• Windows - regions of the screen use to display information (operating system e.g window XP)
• Icons - small pictures used to represent folders and software...
• Menus - lists of options that user can select from
• Pointer - arrow that used to select icons or menus or other things and it also can move around the screen

GUI is sometime called WIMP

-Windows

-Icons

-Menus

-Pointer

Command line interface (CLI)

• User will see the black screen 
• Need to type in the commands to make anything happen e.g. To copy a text file called NOTES from a floppy disc to the hard drive the user would have to type:
  > COPY A:\NOTES.TXT C:\
• Need to learn the whole set of commands 
• There is no visual clue to tell you what to do next!?
• It is quite difficult to use