UX and interaction design

A screen is a still frame from something that moves. Interaction designers work on the movement: the sequence of steps a person takes to finish a task, the feedback after each action, the loading state, the empty state, the error and the undo. Its raw material is what research turned up: the tasks, the goals, the words people use and the places where they currently get stuck. SFIA names the skill user experience design and keeps it apart from the analysis that comes before and the evaluation that comes after; the Interaction Design Foundation roots it in human-computer interaction, the older academic field concerned with how people and computers communicate.

The foundation is structure. Nielsen Norman Group draws a firm line between information architecture, the organisation and labelling of content that users never see directly, and navigation, the menus and links laid on top of it. The order matters: settle the structure, then design navigation that exposes all of it, instead of trimming content to suit a menu you already like. Card sorts and tree tests from UX research check that structure against the way real people expect things to be grouped.

What an interaction designer hands over

• User flows tracing each route through a task, including the branches for failure, cancellation and coming back later.
• Wireframes at low fidelity, where layout and priority get decided before colour can distract anyone.
• State inventories for every component and screen: default, hover, focus, loading, empty, error, success and disabled.
• Pattern choices that reuse conventions people already know, such as a search field, a stepper or a dialog, with a note wherever a convention is broken on purpose.
• Specifications that tell a developer what happens as well as what it looks like, often as an annotated prototype.

Conventions before cleverness

The mistake newcomers make most often is inventing where they should borrow. A novel gesture or an unusual navigation scheme feels like design, but every departure from the familiar costs effort, and every user pays that cost on every visit. Experienced interaction designers spend their originality on the problem that is genuinely new and use known patterns everywhere else. A related trap is designing only the happy path. The screens that decide whether a product feels trustworthy are the ones where the connection drops, the card is declined or the form rejects an entry, and those are precisely the screens most portfolios leave out. Error messages deserve the care of any headline: say in plain words what went wrong, keep whatever the person already typed, and point straight to the fix.

From here the work branches. Towards the surface, UI and visual design gives each state its final form. Towards scale, design systems turn repeated patterns into components a whole team can reuse. Testing ideas cheaply along the way is the business of prototyping, and the same flows have to work for keyboard and screen-reader users, which is where accessibility comes in.