A menu is a list of commands available to the user in the current context. Menus differ from other lists of commands (such as task lists) in that menus are available on demand. The commands they contain are otherwise hidden from the user and they are therefore an efficient means of conserving surface space. There are two main types of menus: the comprehensive drop-down menus (often grouped in a menu bar) and the smaller shortcut menus, which contain core tasks.
To prevent a menu from listing an overwhelming number of commands, you can group related commands in cascading menus. A cascading menu (also referred to as a hierarchical menu, submenu, or child menu) is a secondary menu that appears on demand—when the mouse pointer clicks or hovers over its label. The visual cue for a cascading menu is a triangular arrow displayed adjacent to its label, which appears as a command in the parent menu.