On your clipboard you will find the menu "achievements" - There you will find lot of stuff that, when completed, gives you a varying amount of 'reputation points'.
At 500 points you get one star, at 3000 two stars, at 6000 three stars and at 10,000 reputation points 4 stars. Unlike score, these stars will stay as long as you keep that account (and unlike perks, it will even survive an ingame ID change)
None of this as any further impact on the game, it's purely decorative.
You can disable the showing of stars in chat & roster in the "Achievements" menu as well. I'd recommend that, because it messes up the sorting of names in the roster,
