Nowadays it is pretty much nothing, lol. You were not around when it was formed, so here is some history.
ZU did not used to have these fancy groups, or these visitor messages, or anything of the sort. It was just forums and a chat room, with member profiles for basic info. And we were fine with that.
Then one day, Twilight Wolf comes along and asks to be my friend. I had no idea wot that meant, but I obliged, and he put my name in his sig. Then I did the same. I fell in love with that idea. I got about 12 of my best
ZU friends to allow me to put them in my sig, and soon it was awesome. I then decided, why don't I go further? So rather than just having friends, I made them my army. There were recruitments and enlistments all over the place! I made a special GIF image that included the names and Avatars of all the members, that would rotate to show them. When people saw that, they wanted to join! SO pretty much it was a bunch of people choosing to be my friend, or pledging allegiance to me to fight the war that we supposedly had going on.
Then I went on my mission, they invented groups and now it is just another thing.
Those jerks.