Duplication

There are currently four ways in Blender to procedurally duplicate objects. These options are located in the Object menu.

Vertices
This creates an instance of all children of this object on each vertex (for mesh objects only).
Faces
This creates an instance of all children of this object on each face (for mesh objects only).
Group
This creates an instance of the group with the transformation of the object. Group duplicators can be animated using actions, or can get a Proxy.
Frames
For animated objects, this creates an instance on every frame. As you will see on this topic’s subpage, this is also a very powerful technique for arranging objects and for modeling them.