Keyboard accessibility is one of the most important aspects of web accessibility. Not all users navigate the page with the mouse or a trackpad; some users only rely on keyboard to navigate. Many users with motor disabilities rely on a keyboard. Assistive technology users will also typically use a keyboard for navigation. In addition to traditional keyboards, some users may use modified keyboards or other hardware that mimics the functionality of a keyboard.  Moreover, ensuring keyboard focus, tab order and no keyboard traps is important for the following reasons: 

• Keyboard focus will primarily allow sighted users to know which element from the webpage has focus. If keyboard focus is not present or is difficult to visually see, it becomes a barrier to a user and makes it difficult to access information through a keyboard. 
• Keyboard tab order allows users to properly navigate the page. If the tab order is incorrect and instead starts on the top of the page and then directs the user to the bottom of the page, users will have missed the content in-between those two sections or the user will be forced to use the “tab” key numerous of times before they reach their destination.
• Keyboard traps prevent the user from navigating further in the page.  A user may be forced to perform various workarounds to access the information or may be completely blocked from navigating through the entire webpage again.