Short for Graphical User Interface, the GUI (pronounced as either G-U-I or gooey) was first developed at Xerox PARC by Alan Kay, Douglas Engelbart, and a group of other researchers in 1981. Later Apple introduced the Lisa computer, the first commercially available computer on January 19, 1983. A GUI uses windows, icons, and menus to carry out commands such as opening files, deleting files, moving files, etc. and although many GUI Operating Systems are operated by using a mouse, the keyboard can also be used by using keyboard shortcuts or arrow keys.