Interaction design shapes how users interact with digital products. It covers the flow between screens, the feedback a button gives when tapped, the animation that confirms an action, and the error message that explains what went wrong. The field emerged in the 1980s as personal computers spread and designers realized that software needed to be usable, not just functional. Bill Moggridge and Bill Verplank coined the term in the mid-1980s.

Interaction designers think about states, transitions, and feedback. What happens when a user hovers over a link? What happens when they submit a form? What happens if the connection drops? Good interaction design makes these moments feel natural. Bad interaction design leaves users uncertain. A button that does not change appearance when clicked feels broken. A loading spinner that never resolves creates anxiety. Designers prototype these interactions early, often with simple tools, to test how they feel before writing code.

Core concerns

• Feedback: confirming that an action registered.
• States: default, hover, active, disabled, error.
• Transitions: how screens and elements change.
• Microinteractions: small moments that guide and delight.

Interaction design is not just about making things pretty. It is about making them predictable, responsive, and easy to understand.