It is useful to know the names of the components of the Unity desktop interface in Ubuntu. Without knowing this jargon, it can confusing to search about them online.
The three main components shown in this screenshot are: Desktop (the main area), Launcher (the bar on the left) and Panel (the bar at the top).
The topmost icon in the Launcher is called the Dash (or Ubuntu icon). It is used to launch applications that are not already on the Launcher. It can also be invoked by pressing the Win key.
Tried with: Ubuntu 12.04.1 LTS