Error Prevention (All)
For web pages that require the user to submit information, submissions are reversible, or input errors are automatically checked and the user is given an opportunity to correct them, or a mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.
In plain language
Before finalizing an important submission (like a purchase or a contract), a person needs a way to avoid mistakes: being able to undo the action, having errors flagged automatically, or reviewing and confirming everything before it's sent for good.
Why it matters
Typos and misclicks happen to everyone, but they're even more common for people with motor or cognitive disabilities. Without a chance to review, correct, or undo, a small mistake can turn into a real problem — a wrong purchase, incorrect data submitted with no way back.
In practice
Fails this criterion
A payment page charges the card the moment the button is clicked, with no summary shown beforehand and no way to cancel afterward. If something was entered wrong, there's no going back.
Meets this criterion
Before finalizing the purchase, a summary screen shows all the entered data (address, payment method, items), letting the user review and correct any field before confirming for good.
Test it yourself
Go through any form that submits important information (payment, a contract, personal data). Check whether, before the final submission, there's a review/confirmation screen, automatic error correction, or a way to undo the action after it's sent.