Producing an animation like other types of movies takes place in three stages: preproduction, production and past production.
In preproduction stage, you have to make everything clear and ready to make. It includes storyboarding, layouts, model sheets and animatics.
In production stage, the actual work begins. Some major parts here are layout, modeling, texturing, lighting, rigging, animation, pencil test, backgrounds, traditional ink and paint and camera and digital ink and paint
In postproduction stage, you finalize your animation movie. Here are compositing, sound editing and video editing.
I try to define these terms as simple as I can so you can understand the process of making an animation. You should follow these stages too in order to have a neat and acceptable animation. It is need to be said some of them is being used in 2d animation and some in 3d.