Keyboard usability.
WHO NEEDS IT
People with motor impairments, people using assistive technology, and anyone whose mouse has failed.
WHAT TO TEST
Press Tab repeatedly and move through the page. Can you reach every link, button and form field?
Can you see where you are? There should be a visible indicator on the focused element.
Can you complete a form, activate a button and open the navigation menu?
COMMON FAILURES
Focus indicators removed for aesthetic reasons, leaving keyboard users unable to see where they are Dropdown menus that only open on hover Custom controls built without keyboard support Modal dialogs that cannot be closed Focus order that jumps around illogically
THE SIMPLEST FIX
Do not remove focus indicators. If the default outline is unattractive, style it rather than removing it.
FOR MOST SITES
Standard HTML elements are keyboard accessible by default. Problems arise from custom components and from styling that removes default behaviour.
THE TEST
Five minutes with the Tab key. If you cannot complete your own contact form without a mouse, neither can some of your visitors.