An Animator Controller allows you to arrange and maintain a set of animations for a character or other animated Game Object.
The controller has references to the animation clips used within it, and manages the various animation states and the transitions between them using a so-called State Machine, which could be thought of as a kind of flow-chart, or a simple program written in a visual programming language within Unity.
The following sections cover the main features that Mecanim provides for controlling and sequencing your animations.