Rigging in Blender

Rigging

Rigging in blender consist of three parts:

Skeleton Skinning Controller

Skeleton

This is your bone structure. Just like human, animating models in blender would require you to specify a bone structure.

Bone are order in hierarchy, so that movement from parent will also affect the movement of the child.

Skinning

After you do your modeling you will need to consider weight painting. How much your of your bone affect your modeling.

Joint shared by different bones should have transition with weight since you want both joint to be affecting that pivot point.

Controller

Now when you're animating, yes you could use animate the bone directly.

But if you're doing that why not just drive the Chassis of a car directly? Or just run a PC without it's casing and all it's fancy buttons?

Having a controller is the same idea, you would wrap the bones in shapes: circle, arrow, square, whatever you want the shape to be so that it is easier to control during animation. You don't have to move the bones directly.

Additionally, having controller allows you to have different controls over the same bones, you can have one controller that moves the actual model position, and another that controls the hip movement. They all affect the same bone but do it differently. If you only animate bones that wouldn't be possible.

Hence, controller is an enhancement!

Controller is done by adding constraints with the shape to the bone.]