The application menu is a menu on all versions of the Mac OS starting from System 4.2 (as part of the Switcher utility through to the last version of the Classic Mac OS, Mac OS 9.2.2. Strictly speaking, it is no longer part of Mac OS X. Its existance allowed the user to switch between different application programmes that were open and running. Before System 7, it was a clickable icon. The real menu that lets you select applications (from a menu, of course) was part of the Apple menu.