Cheating

A common complaint regarding Halo's online play has been the widespread cheating which occurred almost immediately upon the game's release. Users exploited bugs in the game and vulnerabilities of the network to win ranked games and thus increase their matchmaking rank.

StandBying
The first forms of cheating that took place were standbying, in which a player would intentionally press the standby button on his/her modem so that everyone in the game would freeze except for the cheater, so that the cheater would be given all the time the cheater needs to accomplish an objective in the game. Exploitation of this glitch may result in an indefinite ban on your Xbox Live Account.

Dummying
Dummying is another cheat that exploded in the Xbox Live community, in which an elite model of a character enters and exits a vehicle in a manner that on the cheater's screen his or her character is still in the vehicle, while on everyone else's screen the character is out of the vehicle and standing still. When the cheater finally decides to exit the vehicle, he or she can grab the flag and then warp back to the body that remains motionless in a different location.

The 1.1 patch fixed this form of cheating.

Softmodding
Softmodding is when someone uses programs in the game console to give themselves the unfair advantage such as Action Replay and other computer programs to give his player unfair capabilities.

Hardmodding
Hardmodding is when someone buys or downloads new programs for their game console providing them with new abilities and powers to give them an advantage over normal game players.

Bridging
Bridging involves computer programs that are used to give a player 'host' status and therefore give him/her the annoying ability to disconnect other players from the game session.

Super Bouncing
A game exploitation called Super Bouncing is labeled cheating by many of the Xbox Live community, and has been described as cheating by Bungie employees when it is used in Matchmaking. Bungie has not made a patch to fix Superjumping, and many people claim that a patch would not be able to fix this exploitation because the whole game engine would have to be changed in order to do so.
 * "Whether it's superbouncing or interrupting weapon animations, just because we don't personally ban you for it doesn't mean it isn't cheating and extremely poor sportsmanship." - Ninja 0n Fire Source

It involves a series of movements, etc, and then jumping onto a certain patch or area, causing the player to bounce to areas of the map that are usually unreachable. This would give players the unfair advantage of sniping points, and could also use them to escape combat.

Button Combos
Another group of glitches, which involve the use of certain button combos to get the upper hand have similarly been described as cheating by both fans and Bungie employees.
 * "By the letter of the law, button glitching is cheating, and we suggest people to report it via feedback." - Tom Gioconda Source