Universal Principles of Design, Revised and Updated

Affordance

A property in which the physical characteristics of an object or environment influence its function.

Objects and environments are better suited for some functions than others. Round wheels are better suited than square wheels for rolling; therefore, round wheels are said to better afford rolling. Stairs are better suited than fences for climbing; therefore, stairs are said to better afford climbing. This is not to say that square wheels cannot be rolled or fences climbed, rather that the physical characteristics of round wheels and stairs better afford the functions of rolling and climbing.1

When the affordance of an object or environment corresponds with its intended function, the design will perform more efficiently and will be easier ...