In form validation, which approach best combines strengths of inline and summary validation?

• A. Inline validation provides immediate feedback during input; summary validation shows all errors on submit; use inline for guidance, but provide summary for final review.
• B. Inline validation is always worse; use summary only.
• C. Show only inline validation with no summary.
• D. Show only a summary after every keystroke.

Answer: (A)

Combining immediate, contextual guidance with a final, all-at-once check gives the most usable form validation. Inline feedback during typing helps users correct mistakes as they go, offering quick, field-specific messages or indicators that guide them without waiting for submission. Then, when the user tries to submit, a summary of all remaining errors is shown in one place, often with a clear list and the ability to jump to the corresponding fields. This lets users see the full picture at once and verify they’ve fixed everything before sending the form.

This approach keeps the experience smooth: you get real-time help that’s unobtrusive and you also get a reliable final review that catches anything that might have been missed. It avoids the drawbacks of the alternatives—for example, relying only on inline validation misses a global view of errors, while using only a summary can feel like a pile of issues to fix at the end and disrupt the flow. A summary after every keystroke is too invasive and distracts from typing.