Error Prevention (Legal, Financial, Data)
For web pages that cause legal commitments or financial transactions, modify or delete user-controllable data, or submit user test responses, at least one of the following is true: submissions are reversible, input is automatically checked and correctable, or a confirmation step is available before finalizing.
In plain language
For anything important — a payment, a legal agreement, deleting data — people need a safety net: a chance to undo it, an automatic check for mistakes, or a review-and-confirm step before it's final.
Why it matters
A single mistaken click on something like "Delete account" or "Confirm payment" can have serious, hard-to-reverse consequences. People with motor or cognitive disabilities are more likely to make an accidental click or entry error, so these safety nets protect everyone from costly mistakes.
In practice
Fails this criterion
Clicking "Delete Account" immediately and permanently erases all the user's data, with no confirmation step and no way to undo it.
Meets this criterion
The same action shows a confirmation dialog explaining what will be deleted and asking the user to confirm before anything actually happens.
Test it yourself
Find any action on the site involving payment, legal agreements, or deleting data. Try it and see whether there's a review/confirmation step, an undo option, or automatic error-checking before it becomes final. If it happens instantly with no safety net, this criterion is failing.