Matchmaking

Matchmaking is a system which allows players or teams to be matched with others for the purpose of playing an online multiplayer game via Xbox Live.

Overview
Matchmaking is a multiplayer system that provides players the ability to enter into a game with less effort. Individuals or teams search for a game, and are matched by the system with other similar players. Once an appropriate number of players is found, the match is made and the game can begin.

Halo 2
Halo 2 does not have any form of custom games search system; instead, it has a simplistic matchmaking system integrated into its Xbox Live feature. There are two options, Optimatch and Quickmatch. Optimatch allows players to select a type of game from a playlist, while Quickmatch simply places you into the last used playtype.

Halo 3
In Halo 3, players can choose from two forms of matchmaking; ranked and social with each having different gametypes. In both playlists, players are awarded Experience Points (EXP) for winning a match. Should they lose, no EXP will be given. However, if the player quits the game during a match, one EXP will be deducted from their account. Halo 3 ' s matchmaking also includes "Double EXP Weekend" which is played only on weekends and awards players double EXP with no penalty consequences should they lose a match. In certain events such as Halloween, special playlists such as Living Dead and Cinco de Mayo are added to the matchmaking and are featured as a "Double EXP Weekend" playlist. These playlists only occur for a short amount of time, usually during the celebration of their respective holiday.

Unlike Halo 2, if a party has a high variability of skill levels in the current playlist, it will acknowledge it as a "mixed party" and will attempt to match with another party or several parties of a similar mix of ranks between the players.

Halo: Reach
So far that is known there will be matchmaking (casual users) and arena (hardcore crowd) such as mlg players.

Rank
For the "ranked" game types, a player has a stat between 1-50. When entering any of the above ranked game types, they are matched with players around their own rank. If the player wins, the Matchmaking software calculates how many experience points the player wins. Likewise, if a player loses, the Matchmaking software deducts a certain amount of experience points from the player. The person's rank corresponds to the amount of experience points that they have.

Unranked games do not effect experience points/ranks, and you can be put together in a game with any player. These game types disregard rank.

Trivia

 * Halo: Combat Evolved is the only game that does not feature any Xbox Live support.