One of many different industries that use 3D animation is architecture,
It enables architects to visualize the blueprints they have in mind, making sure there are no spots where they've gone wrong. It also helps to create a 3D animation for your architectual design because it shows the client almost exactly how it would look finished.
3D animation is used in engineering aswell, for the same sort of reasons as architecture. It helps to have a 3D version of an engineered product which you could move parts about to seehow everything works and is made, it would also help if something goes wrong and you need to diagnose the problem.
3D animation is also used in medicine/surgery, giving surgeons more accuracy and able to make less mistakes because they have blueprints of the body in 3D.
3D animation is used in alot of films and visual effects, It helps create epic scenes, or films which are full of 3D animation. such as transformers, where the robots are added on after as animations.