Decision Cards

Make interface decisions you can defend in any design review.

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Design Decisions · Q1 2027

Learn to make these calls on your own.

These cards are the first of many. The course teaches the reasoning behind each one, with practice rounds and teardowns of real products.

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State & feedback

Inline or Summary

Is it one mistake, or several at once?

Use Inline when

One field is wrong, or you can check it as people leave the field. The fix sits right beside the problem.

Signs it fits

  • A single field has the problem
  • Validation when leaving the field
  • Short forms
  • Format hints for dates and phone numbers

Use Summary when

Submitting finds several problems at once, often in a long form. A summary at the top counts them and links to each field. Keep the inline messages too.

Signs it fits

  • Several errors after submit
  • Long or multi-section forms
  • Checks that run on the server
  • Keyboard and screen reader users need one place to land

The numbers

One error: inline only. Two or more after submit: a summary at the top with a count and a link to each field, plus the inline messages. Validate a field when people leave it, never on every keystroke.

Say this in review

Submitting can surface several server errors at once, so a summary tells people how many there are and takes them to each one. The inline messages stay so the fix sits next to the field.

When it flips

The exception

Very short forms, like a login. Even with two errors, inline is enough: the whole form is already in view.

See it work

Make the call

Card 11 of 15

A 20-field insurance application fails server checks on 4 fields after submit. Inline or summary?

State & feedback
The rule

Say what happened and how to fix it, next to where it happened, without losing anyone’s work.

From the lesson “Errors & recovery”

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