Accessible forms: labels, error messages and autocomplete

Goal

Forms that a person using a keyboard, a screen reader, voice input or browser autofill can complete and, when something is wrong, correct without guessing.

Prerequisites

Native controls (input, select, textarea, button type="submit") rather than styled div elements, and a written list of fields with their validation rules and which ones are required.

Steps

1. Label every control explicitly: <label for="email"> whose for matches the control's id (the WAI tutorial's preferred association). Use aria-label or aria-labelledby only where a visible label is impossible; placeholder text is not a label.
2. Group related controls with fieldset and legend (radio groups, address blocks) so the group name is announced with each option.
3. State requirement in the label text ("Name (required)") and add the required attribute so browsers and assistive technology also know.
4. Add autocomplete tokens to fields about the user: name, given-name, family-name, email, username, new-password, current-password, one-time-code, postal-code. MDN notes that valid tokens satisfy WCAG 2.2 success criterion 1.3.5 (Identify Input Purpose) and that invalid or made-up values used to defeat autofill also fail that criterion, because the purpose is no longer machine-readable.
5. Validate on submit, keep the entered values, and describe how to fix each problem ("Enter the date as DD/MM/YYYY"), not only that it is invalid.
6. On failure, render an error summary at the top with a link to each field, mark each field with aria-invalid="true", and connect its message with aria-describedby; move focus to the summary or first invalid field.
7. When validation runs without a page load, announce the result in a live region (role="alert") so screen readers hear it.
8. Confirm success in text as well as colour, and ask for confirmation before destructive submissions.
9. Test with keyboard only, with one screen reader, and with browser autofill enabled.

Expected result

Each field has an accessible name and a machine-readable purpose; each error is reachable by keyboard, read by assistive technology and tells the user what to change; autofill fills the right fields.

Limits and test basis

Follows the cited WAI tutorials and MDN reference. Automated checkers find missing labels but not unhelpful messages; custom widgets need full ARIA patterns beyond this scope. No measurement is claimed.