Similar to that of the Macintosh, the IIGS System Software provides a mouse-driven graphical user interface using concepts such as windows, menus, and icons. This was implemented by a "toolbox" of code, some of which resides in the computer's ROM and some of which is loaded from disk. Only one major application can run at a time, although other, smaller programs, known as Desk Accessories, can be used simultaneously. The IIGS has a Finder application very similar to the Macintosh's, which allows the user to manipulate files and launch applications. By default, the Finder is displayed when the computer starts up and whenever the user quits an application that is started from it, although the startup application can be changed by the user.