Navigation / Manipulation of an HTML document with the keys of a keyboard.
The tab key is the default key that permits to move from a interactive element to another and therefore change the focus (active element).
On a document, the space will scroll the page (go down on the scrollbar for one page)
On a document by default, the scroll bar will go up/down
As a keyboard is an input device, all event for the keyboard are of the input device category