Interaction design

Interaction design defines the way users interact with a digital product: which gestures or actions trigger which responses, how the interface's states communicate what is happening, and what logic guides navigation. It's the discipline that turns a functional intention into interface behaviour: a button that changes state, a transition that indicates progress, an error message that guides correction.

Interaction design is a component of experience design. UX design covers the overall experience, including user research, information architecture and content strategy. Interaction design focuses specifically on the mechanics of the exchanges between the user and the interface: the actions, the responses, the transitions and the states. Good interaction design is necessary for a good experience, but not sufficient.

Feedback is the interface's response to a user action. It can be visual (a button changes colour after the click), audible (a confirmation beep), haptic (a vibration on mobile) or textual (a success message). Good feedback is immediate, legible and proportionate to the action: the user must always know whether their action has been taken into account and what happened as a result.

Gillian Crampton Smith's model distinguishes five dimensions: words (texts, labels), visual representations (icons, images), physical space (usage context and layout), time (duration of animations, pace of transitions) and behaviour (actions and reactions of the interface). This framework helps to think about interaction in a complete way, beyond the visual aspect alone.

You start with low-fidelity prototypes to validate the interaction logic: clickable wireframes are enough to check the consistency of the sequences. You then increase fidelity with animated prototypes (Figma, Principle, ProtoPie) to test the transitions and states. Think-aloud user tests are particularly useful to check that the interface's feedback is understood and that the sequences are intuitive.