Ratings?

Why is it that if I beat someone with 400 higher rating (900 v. 1300) they drop by over 200 rating but I only gain 15..

Ratings adjustments depend on the following: a) game outcome, b) ratings difference between players, and c) the RD (i.e., ratings deviation) factor of BOTH players. The RD factor is the most mysterious of these issues. The RD factor is inversely proportional to playing frequency, so a player who plays often has a low RD, and an player who plays infrequently has a high RD. If two players play each other and both are frequent gamers, then the ratings adjustments to both players will be smaller because their ratings are less uncertain. If the RDs are quite different, then adjustments can be quite different.

Here's a link to more information on the Glicko Rating System used here at chess.com:

http://support.chess.com/Knowledgebase/Article/View/16/0/how-do-ratings-work

With your current Glicko RD of 37 your rating will change very slowly. There is a high confidence your strength is within 74 (2 times 37) points of 928.

http://www.glicko.net/glicko.html

"Because a player in the Glicko system has both a rating and an RD, it is usually more informative to summarize a player's strength in the form of an interval (rather than merely report a rating). One way to do this is to report a 95% confidence interval. The lowest value in the interval is the player's rating minus twice the RD, and the highest value is the player's rating plus twice the RD. So, for example, if a player's rating is 1850 and the RD is 50, the interval would go from 1750 to 1950. We would then say that we're 95% confident that the player's actual strength is between 1750 and 1950. When a player has a low RD, the interval would be narrow, so that we would be 95% confident about a player's strength being in a small interval of values."

Ok can you make a tl;dr version of that and put it in basic English so I don't have to get a dictionary