Principle 3 Understandable · Guideline 3.3: Input Assistance
3.3.1 Error Identification
Input errors must be identified – in text.
What this means in practice
A red border alone is not enough. Text must say which field is affected and what is missing. The message should also be announced by the screen reader.
Normative wording
The binding text lives at the W3C. What you read here is our own faithful rendering – not a quotation.