A screen reader user typically uses the keyboard to navigate digital content. Keyboard focus refers to the element that can receive keyboard input at a given moment. On a webpage, the element with keyboard focus is outlined to help a sighted user know where the focus is, unless the outline has been disabled. Because the outline is part of accessibility, the AUL advises that the outline remain enabled. It is not only important to make sure that all operable elements -- links, buttons, form fields, drop down menus, etc. -- can receive keyboard focus, it is also important that they receive focus in an order that makes sense. As a general rule, elements should receive focus in the same order as someone would move through them visually, left to right and top to bottom. For example, tabbing or using other navigation keys would move through the content starting with main navigation, secondary navigation, main content, and ending with the footer.
For more information, see: a video about tab order.
Relevant issues from the database include: Tab Order Does Not Make Sense, and Element Does Not Indicate User Can Interact with It.