Consistency

Visuals must be consistent to help the users find their way through an interface. Consistency allows users to transfer existing knowledge to new tasks, learn new things more quickly and focus more attention on tasks. This is because they do not have to spend time trying to remember the differences in interaction. By providing a sense of stability, consistency makes the interface familiar and predictable. Consistency is important through all aspects of the interface, including names of tasks, visual presentation of information, operational behavior, and placement of elements on the screen and within windows.

There should be a standard set of forms, colors, shapes, textures and other design elements in an interface. The set of controls that help users orient themselves and anticipate what will happen when they touch something should be clear and the same throughout the interface.