Links and Constraints
The core of a rig are the links and constraints between the bones, the layers or the properties. You can view the constraints as the strings and mechanisms which drive a puppet; the bones are the armature, the handles are the animation controllers.
There are several different kinds of constraints, but they almost all work the same way, in a cause-and-consequence / parent-and-child / master-and-slave relationship.
The Links and Constraints panel
The Links and Constraints panel
The top toolbar of the Links and Constraints panel contains a few useful tools related to parenting, properties and transformations. Below the toolbar, you’ll find all the available constraints.
The Links and Constraints toolbar