The last tool we'll cover in this article is the use of animation layers and masks. Animation layers are the way to organize your animation states into separate groups that can be blended or overridden by each other. For example, you can use an animation layer to add a facial expression or a gesture to your character without affecting their body movement. You can create and edit animation layers in the Layers tab of the Animator Controller. Animation masks are the filters that you apply to animation layers to specify which parts of your character are affected by them. For example, you can use an animation mask to isolate the upper body or the lower body of your character. You can create and edit animation masks in the Avatar Mask Inspector.