Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.
Testing & RemediationHow to test: Open your website in a browser of your choice and begin to navigate the site using only the keyboard (use the Tab key to move focus through all elements on the page). Visually confirm that all elements receive a visible focus indicator when they are navigated to. How to remediate: Generally the easiest way to remediate issues related to this Success Criterion is to use the CSS focus indicator.
Questions and Answers
Nearly all elements can be given focus, and have their focus order changed using the 'tabindex' attribute. Elements on a page will be given focus in the order of their tab index. W3 Schools has a great explanation of tabindex here.
To navigate a website with the keyboard, you can start by hitting the tab key. You should see an indicator on the element that has focus. If it is a link, you can hit enter to go to it. While going forward through the tab keys is done with tab, going backwards can be done by hitting the shift key in addition to the tab key. When it comes to various input elements (radio buttons, select boxes), the arrow keys can be used on them once the element has focus.
This question depends on a number of factors including size of site, desired level of conformance, your developer's understanding of accessibility techniques, etc. Accessible Web is here to help. Reach out and we can discuss your site specifically.