An affordance is a quality of an object that suggests how it can be used. A door handle affords pulling or turning. A button affords pushing. A flat surface affords placing things on it. The shape and design of objects give us clues about what we can do with them, often without anyone needing to explain it.

The concept was developed by psychologist James Gibson, who noticed that we perceive objects partly through what they allow us to do. When you see a chair, you don't just see wood and fabric: you perceive something that affords sitting. A staircase affords climbing. A cup affords gripping and drinking from.

Good design makes affordances obvious. Think about how a door with a flat metal plate suggests you should push it, while one with a handle suggests pulling. When designers ignore affordances, things get confusing: you've probably pushed a door that said “PULL” because its handle made pushing seem like the natural thing to do.

Teachers and game designers also think about affordances in learning environments. A blank sheet of paper affords drawing or writing. Building blocks afford stacking and creating. Even digital things have affordances: a blue underlined word on a screen affords clicking because we've learned that pattern means it's a link. Understanding affordances helps us design better tools, spaces, and experiences that people can use naturally and intuitively.