Validation

Do

• Use inline validation after the user fills out the field (unless it helps them while in the process).
• Show the user where the error occurred and provide a reason.
• Put the message in red after the question input.
• Use a red border to visually connect the message and the question it belongs to.
• As well as showing error messages next to questions, an error summary should also display on submit, at the top of the page to summarise any errors a user has made.

Don't

• Don’t use inline validation while the user is typing — unless it helps them — like in the case of creating a password, username, or message with a character count.