Graphical User Interface (GUI)

Graphical User Interface (GUI) is a kind of user interface in which elements (menus, buttons, icons, lists, etc.) presented to the user on the display, are executed in the form of graphic images.

In the GUI, the user has random access (through input devices such as a keyboard, mouse, joystick, etc.) to all visible display objects (interface elements) and directly manipulates them. Most often, GUI interface elements are implemented on the basis of metaphors, and display their purpose and properties, which facilitates the understanding and mastering of programs by untrained users.

The graphical user interface is part of the user interface (UI) and defines interaction with the user at the level of visualized information.

Classification

• Simple: typical screen forms and standard interface elements provided by the subsystem of the GUI;
• True-graphic, two-dimensional: non-standard interface elements and original metaphors realized by the app's own tools or by a third-party library;
• Three-dimensional.

DWIM

One of the requirements for a good graphical interface of the software application is the concept of "Do What I Mean". DWIM requires that the system works in a predictable way so that the user intuitively knows in advance what action the program will perform after receiving the command.

Advantages

• The graphical interface is user-friendly, especially for people who’ve used other apps. Usually, the users can easily find in the interfaces similarities with other programs, working on the same operational platform, like the hamburger icon for mobile app menus on smartphones or the printer sign for printing documents.

Disadvantages

• Greater memory consumption compared with the text interface;
• It is more difficult to organize remote work;
• Automation must be integrated in the structure of the DWIM at the pre-development stage. In other cases, quite often it’s easy to develop a new app instead of adding such features to the existing system, as automation is impossible for the current structure.
• The graphical interface is not always "friendly" for users who have begun to familiarize themselves with the computer from the command line interface.

Examples of systems using the GUI: Mac OS, Android, iOS, Microsoft Windows, GNU / Linux, GEM, Solaris,  Atari TOS, BeOS, MeeGo.