Interaction design shapes how users interact with digital products. It covers the flow from one screen to the next, the feedback when a button is pressed, the animation when a menu opens, the error message when something goes wrong. The goal is to make the interaction feel natural. The user should not have to think about how to use the product. They should just use it. When interaction design works, it is invisible. When it fails, the user notices immediately.

The discipline draws on psychology, ergonomics, and computer science. It considers how people perceive, decide, and act. Fitts's law predicts how long it takes to move to a target. Hick's law predicts how long it takes to choose between options. These principles guide layout and flow. Interaction designers prototype extensively. They test with real users. They watch where people hesitate, where they click by mistake, where they give up. Each observation informs a revision. The process is iterative. Small changes accumulate into a smooth experience. Interaction design also covers microinteractions. The subtle animation when you like a post. The haptic feedback when you toggle a switch. The progress indicator when a file uploads. These details build trust. They tell the user that the system is responding. Without them, the product feels dead. With them, it feels alive.

Interaction design elements

• Flows — the path a user takes through a task
• Feedback — the response to a user action
• Microinteractions — small animations and responses
• States — default, hover, active, disabled, error
• Transitions — how screens and elements change

Interaction design is the choreography of a digital product. It determines how the product feels in use.