Where is the point/rating system explained?

I've played the computer three times. Lost to Jim (600) once and am 1 loss and 1 win against Martin (250). My rating is 400.  

Where is the docs for the point/rating systems?

Thanks David

Happy to run down the article on Chess.com's rating system for you but the bots are all unrated so your rating will never change if that's all you play.

Here you go....

https://support.chess.com/article/210-how-do-ratings-work-on-chess-com

baddagno,

Thanks for the link. So, does everyone start off at 400? 

No, you have a choice when you sign up, or so I've read.  You self identify your skill level and get the appropriate rating.  Luckily the Glicko system pretty quickly sorts out your approximate rating in case you're way off in your self evaluation.  And of course you are quite welcome...

Thanks

You mean the open challenges?  Looks like green is rated and black is unrated, but that's just from rolling my cursor around.  Might be more to it than what's obvious; I don't know...