One of the most important aspects of accessibility is managing focus and user interaction. By default, all links and form controls can get focus. That allows you to use the tab key to navigate between them and, when one of the elements has focus, activate it by pressing the enter key. This paradigm works amazingly well regardless of the complexity of your web application. As long as a keyboard-only user is able to navigate between links and form controls then it’s possible to navigate the application.