User groups are XenForo's primary method of assigning roles to the users of your forum. This allows you to assign permissions, titles and other customizations to users.
Ah! I didn't know that. Thanks for letting me know. Essentially, I am trying to cut down on poll spam. So I set up a group called Noobie. I wanted that as my initial group until the user had 10 posts, then they get promoted to the Registered group. But it seems they are there already! Hmmm, will have to think again.
So I will have like 50K users in the Registered group. Remove the poll permissions from that group. Then set a promotion so that Registered members get added to a group called PollCreators if post>10? Something like that?