A fullscreen object occupies the entire screen.
An application is considered to be fullscreen if it takes up the full area of the screen, as opposed to being in a window.
Common uses for full-screen include playing videos, viewing photo or playing games.
In Microsoft Windows 8 and above, Windows Store applications are shown in a full-screen mode. Full screen mode can be entered/exited using the F11 function key.
In Mac OS X Lion and above, a number of applications have a full-screen mode, that can be activated by clicking the arrows control in the top-right corner of an application window.
An element in a Web page can be taken full-screen by using the Fullscreen API.