Step 1. Introduction
The focus or tab order is a sequence in which the user goes through all the interactive elements on the web page, such as links, buttons and controls.
Keyboard and other input devices users need to be able to navigate to and activate any interactive element on a website in order to successfully use it - just as you do.
If the tab order is affected by the decisions discussed in the next steps, it would confuse your users and waste their time.