I have never used this funtion before now, and I'm wondering why not.
The rest of you users may have already been using this funtion. If so my apologies.
I had a part that had a bunch of 2d entities that I was moving around to get them located just right. (The actual file was lots of engraving.) And after I had selected them numerous times over and over to move and rotate them, the light bulb went on.
I used the Group funtion to group the parts that I wanted to act as one entity.
That way I only had to select the group and all the entities in that group would be selected. Much easier to move and copy things and rotate around.
When I was happy with the results, then I used the Ungroup funtion and all is back to normal.
Not something you would use every job, but pretty handy in certain instances.
The drawing below is a sample. The inner (purple) entities are grouped as one entity. And the outer (lime) entities are grouped as one entity.
You can do about the same thing with different layer or colors. But some times this may be the way to go.