The Unity desktop is a desktop GUI developed by the Unity Project 2010 and maintained by Canonical. Unity is currently found within the Ubuntu Linux operating system. Unity's emphasis is on simplicity and intuitiveness, and it maintains enough similarity to more traditional desktops that it is easy for users to use and understand.
Techopedia explains Unity
The Unity desktop is a little different than what most end users are used to, and the primary reason behind this involves the deployment of the vertical task manager on the left-hand side of the screen. This has been termed the "launcher." This is somewhat similar to the various Mac desktops that have the launcher panel on the bottom of the screen.
The launcher is the main interface between the end user and Unity, and it includes icons to commonly used applications. If a desired application is not currently in the launcher, Unity has a search feature that allows the end user to type in the name of a given application in order to gain access to it.