In Eclipse, menus can be used to trigger user actions. These menus can be displayed at the top of the application window (or top of the screen on macOS). Menus can also be associated with a view through a contextual popup using the right mouse button.
A menu can be associated with a command, which represents a generic operation. The command is then dynamically associated with a handler, which is the code that executes the operation. This allows a generic operation (such as copy) to be executed by different handlers depending on the context.