For easy access to the controls for groups on the ribbon, locate the Home tab, Groups panel.

The commands in the panel include Group and Ungroup, plus . . .


Group. Find
The objects now belong to a group.
With group selection turned on, the copy of the group is also a separate group.

Group Selection On/Off Find
Groups panel
Ungroup. Find
So, the next time you spend time selecting an intricate set of objects, consider whether taking the extra step of using the Group feature will save you time selecting and reselecting the same objects.
For more information, watch this video by CADLearning, an Autodesk Authorized Publisher.