Affordance
Affordance is the relationship between an object's properties and a person's capabilities—defining what actions are possible.
Case 1: Teapot (Physical Affordance)
The handle affords holding; the spout affords pouring.
Case 2: Digital Buttons (Perceived Affordance)
On screens, we can't physically press. Designers use shadow, highlight, and depth to convey clickability.
SUBMIT
Weak AffordanceSUBMIT
Strong Affordance