Menus are one of the primary ways to interact with applications in a GUI interface. Menus are typically accessed through one of two ways.
Clicking on a particular menu at the top of the screen (e.g. the File menu or Edit menu)
Right clicking to bring up a context menu
Menus contain common actions for applications. Often these actions are accessible via keyboard shortcut.
As of Ubuntu version 11.04, application menus are typically found in a global menu at the top of all screens. Before this version, application menus were contained in the application window itself.