unrated

I tend to play unrated when I'm playing with a handicap (ill, time-odds, piece-odds) or when I'm experimenting (new opening, new time control). I can also answer questions about the game before we're finished. Unrated means exactly what it sounds like--your rating will not be affected in any way by the game.



Can anyone explain to me the purpose of an unrated game. What does the rule book say? Is it playing just for fun or something?