For questions regarding the Unity desktop environment, including configuring and using Unity. Unity has been the default Ubuntu desktop environment from Ubuntu 11.04 to Ubuntu 17.04.
Unity was default interface for Ubuntu on PCs, TVs, and phones. It is the result of design and development work lead by Canonical and the Ubuntu community. Unity became the default Ubuntu desktop environment with the release of Ubuntu 11.04. In Ubuntu 17.10 and later Unity has been discontinued in favor of GNOME as the default desktop environment for Ubuntu.
Based on the Compiz window manager, Unity has been Ubuntu's default interface since 11.04. An early version of Unity was also used as the interface of Ubuntu 10.10 Netbook Edition. Since Ubuntu 11.10, a 2D version using the Metacity window manager is available as the fallback for computers not powerful enough to run Compiz.
This tag is for questions relating to Unity in general.
If you have a question about a specific part of Unity and aren't sure what it is called, please see http://askubuntu.com/questions/10228/whats-the-right-terminology-for-unitys-ui-elements