What is a GUI? The well made up definition is ‘A program interface that takes advantage of the computer's graphics capabilities to make the program easier to use. Well-designed graphical user interfaces can free the user from learning complex command languages . On the other hand, many users find that they work more effectively with a command-driven interface, especially if they already know the command language.' As webopedia says. To make this a little easier to understand I will give you a few examples of GUI's.
Windows is a good example of a GUI. It helps construct simple writing documents without having to use complicated HTML. You can paste pictures, type and create newsletters, etc. that can be attached easily to the internet and other sources of the computer. This is very helpful who those that are not skilled in computers.
Because of GUIs people are able to understand computers more skillful and completely.