2. Command Line Interface (CLI)

A Command Line Interface allows the user to interact directly with the computer system by typing in commands (instructions) into a screen which looks similar to the one below:

You cannot just type in any kind of instruction of course, because the computer will only react to a definite set of words.

These command are very specific, for example in DOS you could type in:

copy c:\item.txt   d:\

That tells the machine to copy the file 'item.txt' that resides in the root directory of drive C: into the root directory of drive D:\

Before Windows was developed, this type of user interface was what most people used to get the computer to follow instructions. Nowadays, very few people have the knowledge to be able to use a command line interface.

An example of this type of interface is DOS (Disk Operating System).