Unity 3D Developer Question:

Prefab in Unity 3D is referred for pre-fabricated object template (Class combining objects and scripts). At design time, a prefab can be dragged from project window into the scene window and added the scene's hierarchy of game objects. If desired the object then can be edited.

At the run time, a script can cause a new object instance to be created at a given location or with a given transform set of properties.