forms

Decision time grows logarithmically with the number of equally likely choices, so the tenth option costs far less than the second.

Law · Decision making

Working memory holds a small number of chunks, so the design lever is what counts as a chunk, not the raw item count.

Law · Memory

Every system has irreducible complexity. The only question is whether the user absorbs it or the product does.

Law · Complexity

Unfinished tasks stay mentally active, which is why visible progress pulls people back to complete them.

Law · Motivation

Be liberal in what you accept and conservative in what you send, which for interfaces means accepting messy input and returning clean output.

Law · Robustness

Work expands to fill the time available, which is why open-ended tasks in an interface tend to sprawl.

Law · Behaviour

Better than a good error message is a design in which the error cannot occur.

Heuristic · Nielsen heuristics

Recognising something on screen is far easier than remembering it, so keep the information visible.

Heuristic · Nielsen heuristics

Error messages should say what happened, why, and what to do next, in plain language.

Heuristic · Nielsen heuristics

Show the common case first and reveal the rest on request, so complexity is available without being present.

Principle · Complexity

Restricting what is possible is the cheapest way to prevent an entire class of error.

Principle · Interaction

The claim that decision quality degrades over a sequence of choices. Popular, intuitive, and on much shakier experimental ground than its usage suggests.

Psychology · Attention and effort

Things placed close together are read as belonging together, before anything is read.

UI foundation · Gestalt principles

How many vertical divisions the content occupies, which affects scanning as much as it affects fit.

UI foundation · Layout

Lines that separate, which should be the second choice after space rather than the first.

UI foundation · Form and depth

Suggestions as the user types, which turns recall into recognition when it is fast enough.

Pattern · Finding

Checking input at the right moment, which is rarely while the user is still typing.

Pattern · Forms

Actions that remove or destroy, which need separation in space, distinct styling and a recovery path.

Pattern · Safety

Breaking a long task into steps, which reduces per-screen load but adds navigation cost and abandonment points.

Pattern · Forms

Triggers an action. If it navigates somewhere, it should be a link instead.

Component · Actions

Free-form entry, where the label, the hint and the error placement do most of the work.

Component · Forms

Choosing one option from a known set, which is the wrong control below about five options.

Component · Forms

Independent on or off choices, where the label is part of the target.

Component · Forms

One choice from a small visible set, where seeing all the options is the point.

Component · Forms

An immediate on or off setting, which must actually take effect immediately.

Component · Forms

Selecting from a continuous range, which is imprecise by nature and needs a numeric partner.

Component · Forms

One of the hardest components to get right, and one where typing is often faster than picking.

Component · Forms

A persistent message tied to a context, which is where anything requiring action belongs.

Component · Feedback

Parallel views in one space, which works only when users never need to compare across them.

Component · Navigation

Content revealed below a trigger, a term that covers three different components and causes confusion.

Component · Navigation

Signing in is a gate in front of the thing people came for, so every decision is about removing steps without removing safety.

Pattern · Account

The most scrutinised form in any product: total cost visible early, card entry forgiving, and failure states specific.

Pattern · Commerce

Shows where the reader is in a sequence, how much is left, and whether they can move between steps.

Component · Navigation

Say what happened, why if you know, and what to do next, in that order and in plain language.

UX writing · UX writing

Writing that does not exclude, misgender or make assumptions about the person reading it.

UX writing · UX writing

Designing so the product can be adapted to other languages and regions without being rebuilt.

UX writing · Localisation

Label the outcome, not the mechanism, and make the label make sense read on its own.

UX writing · UX writing

Say what the field wants, why it is needed, and what format is acceptable, before the reader gets it wrong.

UX writing · UX writing

Deliberately moving focus when the interface changes, so keyboard and screen reader users are not stranded.

Accessibility · Operable

Telling assistive technology that something changed, when focus did not move to say so.

Accessibility · Robust

Colour may reinforce meaning but must never be the only thing carrying it.

Accessibility · Perceivable

Errors must be identified in text, described specifically, and accompanied by a suggested fix where one is known.

Accessibility · Understandable

Every input needs a persistent label, and format requirements must be stated before the user types.

Accessibility · Understandable

A retailer required registration before purchase to build its customer database, and lost the sales it was trying to capture data about.

Case study · Ecommerce

Splitting a long form into steps did not raise completion until the team also saved progress and let people come back.

Case study · Forms

A review pass for any form, covering structure, labelling, validation, errors and accessibility.

Checklist · Forms