Experience point

EXP (Experience Points) are awarded to players based on their performance in a Halo 3 multiplayer match. Along with skill, EXP determines a player's rank and advancement in rank. Points are awarded thusly :
 * Win: 1 EXP
 * Lose: 0 EXP
 * Quit/Disconnect: -1 EXP

EXP is only lost when a player leaves a match before it is over. This penalty typically only applies to team matches, in any playlist. Also, the game counts a disconnect as quitting, so if your internet connection dropped or if you unplug your router, you will still be penalized as if you had quit the match through the menu.

In a free-for-all match, a player is considered to have won if he finishes in the top three, or in a team match, a player wins if his team wins.

Also, losing five ranked playlist matches in a row will cause you to lose an EXP point