Groups associate several objects together without actually making them a single object. The area where groups are particularly useful is when you clone sets of objects that you need to keep together per copy. Groups are managed under the Group menu in the main toolbar. There are just a few tools, and if you use groups a lot, it is handy to put the Group tools into the Quad menu.
A group can be animated as a root of the objects it collects together. The idea of a group precedes the idea of an assembly, which precedes the idea of an XRef, which precedes the newer, more elaborate Create | Helpers | Container concept. Consequently, groups are simplest. Groups are stored locally in the scene, not externally as a file. Containers are saved to a file. You can find a PDF supplement on Containers and XRefs in the provided content for this chapter.