In programs with a graphical user interface, you can call subprograms by activating command buttons (button) or menu entries (menu bars, context menus).
Based onhttp://de.wikipedia.org/wiki/Menü/Computer is:
“A menu… a form of interactive user guidance for computer programs with a graphical, character-oriented or rarely language-oriented user interface (GUI, TUI or VUI). It makes it possible to select the desired command from an offer (hence' menu') and execute it without having to know and apply precise control commands. Today, menu bars are standard in' Common User Access'….. Menus are usually grouped hierarchically into menu bars at the edge of the screen or window, which summarize the commands under keywords or symbols, the basic menus. If these terms are selected, a list opens up, the dropout menu with the corresponding menu items, which then trigger commands (programs, modules, actions of the program). Special submenu items do not execute a function directly, but open another menu level, as a further dropout, as a pop-up menu or as a dialog box. All in all, the most important functions that the operating system or application program offers are listed. A variant is a toolbar with icons, the toolbar designed for direct commands rather than hierarchical selection ”.