Focus Visible
Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.
In plain language
When someone navigates using the keyboard, every focused element must show a visible indicator — like an outline or highlight — so the user always knows where they are on the page.
Why it matters
Without a visible focus indicator, keyboard users are navigating blind. They press Tab but have no idea which element is currently selected. It's like using a mouse with an invisible cursor.
In practice
Fails this criterion
A user presses Tab through a form, but no element shows any visual change when focused. The user has no idea which field is active.
Meets this criterion
Every interactive element shows a clear, high-contrast outline when focused. The user always knows their position on the page.
Test it yourself
Press Tab through the interface. If at any point you can't see which element is focused, this criterion is failing. Look for a visible outline, border change, or background change on the active element.