6. Keyboard accessible

Is the interface fully keyboard accessible? Can a person use a keyboard alone to complete all tasks, and get access to all information?

Reference: Understanding Success Criterion 2.1.1: Keyboard

How to test:

Unplug your mouse (Optional).
Use a keyboard alone to navigate the user interface. Press the Tab key to work down the page/screen, and Shift-tab to work up the page/screen. Ensure content can be tabbed through in a logical and hierarchal order.
Pay attention to the focus indicator. This indicator is used to help users browsing with a keyboard know where they are located in the page. If the focus indicator disappears, then it is not keyboard accessible.
Check that all links/buttons/form fields can be focused and activated with the keyboard. You need to press 'Enter' or 'Spacebar' to activate controls. Some controls, like radio buttons and drop-down lists, will require you to use the arrow keys.