Interaction Design

What it is

Interaction design shapes moment-to-moment behaviour: what happens when someone taps, what the interface says while it works, what it shows when it fails, and how one step leads to the next. It is the discipline of states and feedback, not of how things look — that is visual design, and the two are decided separately even when they are drawn together.

Why it matters

Most complaints about an interface are not about its appearance but about its behaviour: a button that gave no sign it was pressed, a form that lost the input, a state that never seemed to end. These are invisible in a static layout and surface only when someone uses the thing. Interaction design decides them deliberately rather than by default, and the cost of getting them wrong is trust — the user presses twice, then stops trusting the interface entirely.

In this track

1. States and feedback (03-design-ux/44-interaction-design/01-states-and-feedback) — what the interface shows while it works, waits, succeeds and fails.
2. Flow (03-design-ux/44-interaction-design/02-flow) — how steps connect, how people move back and sideways, and where the path should branch.

Prerequisites

• Prototyping (03-design-ux/40-prototyping)

Go deeper

• Prototyping (03-design-ux/40-prototyping) — read this first; states are hard to judge until they are clickable.
• Visual Design (03-design-ux/10-visual-design) — the other half: hierarchy, contrast and layout on top of the behaviour.
• Accessibility (WCAG / a11y) (02-frontend/11-accessibility-wcag-a11y) — the behaviour that has to work for keyboard, screen reader and reduced motion.
• Usability Testing (03-design-ux/33-usability-testing) — checking whether the feedback actually reads as feedback.