Definition
In 3D computer graphics, 3D rigging is the process of creating an ‘invisible’ bone structure that defines how an object moves. This skeleton structure simplifies the actual animation process. 3D rigging helps in forming an invisible bone structure that defines how the movement will take place in animation.
An animation or 3D rig can be seen in a 3D viewpoint during the process of rendering but not in the final render. Through this process, you can control the movement of the 3D image easily and make any changes in the 3D objects according to the requirements of the animation. 
Uses of 3D Rigging in Animation
Rigging is used in animation widely for the sole purpose of animating 3D objects, backgrounds, and characters. You’ll find this technique being used in TV shows, movies, and video games. In the media industry rigging is an important step that is focused highly upon during the animation process. It is imperative for creating good quality animation that your rigging phase runs smoothly and is detailed.
3D Rigging is not just a feature used for human modeling but it can also be used for rigging an object with any respective action. The Pixar lamp is one of the first 3D models to be rigged.
3D rigging is also used in animations that are created for the Medical and Education sectors where visuals are required to teach and demonstrate the various phenomenon. For example, medical animation professionals make use of this technique to create life-like organs, systems, and bones of the human body. It will allow practitioners to come up with realistic replications of how the body will work and process something. 
Additional information
Rigging provides the animators easy control over the movements of a model, hence making it easy to animate a character. It is one of the most widely used techniques in 3D animation. The main 3D rigging software that is used in the animation industry are Autodesk Maya, Hudini, Cinema4D, Photoshop, 3ds Max, ZBrush, and Blender. Professional riggers often use a combination of rigging software and techniques to get to the desired outcome.
