A character rig is a skeleton which is bound to a 3D model. It is made up from joints, which when bound to the model can be used as handles for moving the character into different positions.Once the skeleton is formed , you can create IK chains which calculate the position of joints so that the movement can be created without the need to move every single joint effected. Another factor connected to rigging is weighting. weighting is choosing how a movement will effect certain parts of the model. Its very important as if not done properly, when a joint is moved, the model will distort.
Example of a simple character rig.
Example of weighting.
