All objects have a context menu which is activated by pointing at the object and depressing mouse button 2 (this is also known as "popping up" a menu). These menus are contextual because the content depends on the capabilities of the individual object. They can often be extended by the user so new functions can be added to the object.
Usually these context menus reflect the capabilities of a single object. One has to be careful when selecting several objects and then activating the context menu of one of the objects. This menu then shows only those choices which pertain to all of the selected objects.