Customers want to have a way to define pre-fabricated set of assets, usually a group/collection of 3D models with pre-defined animations that they can then drag'n'drop in to the current slide/scene/project they are working on.

The prefab acts as a template from which you can create new object instances in the scene. Any edits made to a prefab asset are immediately reflected in all instances produced from it but you can also override components and settings for each instance individually.