1. How do people communicate with computers?

2. User Interfaces
Software

3. User Interfaces
A user interface is the way the user (person) and the computer exchange information and instructions.
There are three main types: -
command line
menu driven
graphical user interface (GUI).  

4. Command Line Interfaces
Older operating systems such as MS-DOS are often called Command Line Interfaces or CLIs.
They are text based, and the user has to type in what they want to do using commands the computer will understand.
They work very quickly, and don’t use up much memory or hard disk space, but they are difficult to use unless you know the commands really well.

5. 2. Menu Driven Interfaces
The user is offered a simple menu from which to choose an option. One menu often leads to a further menu.
Features of menu driven interfaces include:  
They are easy to use as the user does not have to remember sets of commands.
They are user friendly - you can often guess your way around the options.
They can be irritating if there are too many levels of menus to move around.

6. 3. Graphical User Interfaces (GUIs)
GUIs use pictures called icons to represent files or buttons, and the user clicks on the button with a pointer moved by a mouse.
Features of GUIs include:  
They are much easier to use for beginners.
They enable you to easily exchange information between software using cut and paste or 'drag and drop'.
They use a lot of memory and processing power.
They can be much slower to use than a CLI for expert users.
Windows, OS/X and Linux Operating Systems are all graphical user interfaces.  

7. Designing a User Interface
A good user interface should:  
be attractive and pleasing to the eye
allow the user to try out different options easily
be easy to use
use suitable colours for key areas
use words that are easy to understand aimed at the type of user
have online help
It also should consider the needs of the users. For example, young children are likely to prefer pictures to words.