Provisional & established ratings?

You have a provisional rating if you have played less than 20 rated games in a given rating category (bullet, blitz, standard, wild, bughouse, losers, 1-minute, 3-minute, etc).
Once these 20 games are completed the rating becomes established.

A provisionally rated player's rating will fluctuate dramatically. The rating of an established opponent of a provisionally rated player will hardly change at all.
In general, an established rating can gain or lose at most 32 points in one game.

See "help provisional"  and  "help ratings" for more info on ICC's rating system.