User Profile: Group Membership?

Hi people,

So, a simple and fast question. Why does a thing like “Group Membership” exists if we can’t use it ( or am I the only one not knowing how to use it ). Because I’ve met that little crappy thing in almost every forum and i have no idea why is it there… Never saw anyone in a “group” or whatsoever… Can someone enlighten me ?

Thanks mates,
Biro Barna