Every use of a digital product is a loop of act and answer: the user does something, the system responds, and the exchange repeats until the task is done. That loop is the atom of user experience. An interaction is one round trip between intent and response.
In this glossary topic:
What is an interaction?
An interaction is a single exchange between a user and a system: an action, the system's response, and the feedback that confirms what happened. Clicks, taps, gestures, keystrokes, and voice commands are all interaction inputs; the responses and their timing are what make the exchange feel instant, sluggish, or broken.
What forms do interactions take?
The input vocabulary keeps widening: pointer and touch remain the defaults, joined by gestures, voice, keyboard-only paths, and increasingly conversational and AI-mediated exchanges where the user states an outcome rather than operating controls. Each form carries its own feedback expectations, which is why the same feature can feel polished with a pointer and clumsy by voice.
Why do interactions matter?
Products are judged loop by loop: an interface is only as good as its worst frequent interaction. Response time, feedback clarity, and error tolerance at this atomic level compound into what users later describe as the product feeling fast, reliable, or frustrating. Designing these exchanges deliberately is the work of interaction design, the discipline built on exactly this unit.
