Cheating is the act of a player or team breaking the rules of quizbowl to gain an unfair advantage. It is a form of grievous misconduct - players who are known to have cheated are typically banned permanently, though this is not always the case.
It should go without saying that no player should ever cheat.
Cheating in quizbowl almost always refers to the act of obtaining outside information about the questions being played. This section is not a guide on how to cheat - if anything, it is a guide on how to prevent cheating. Do not ever attempt to do any of these things.
Obtaining packets or questions beforehand
In the case of Andy and Joshua, the culprit was a flaw in the NAQT writing software Ginseng, which allowed writers to view some or all of questions that they were eligible to play - this flaw was discovered in 2013 and resulted in the vacating of Harvard's titles at the 2010 and 2011 ICTs.
In the case of Amit (and Joshua, in one instance) the method of choice was social engineering. The cheater posed as an individual who had a legitimate reason to access the questions via email and was able to receive the packets. To avoid this, do not ever give packets to individuals who you cannot 100% confirm as legitimate.
In the case of Stephen, the questions were already uploaded to the archive and he simply downloaded them before the tournament. Any tournament which happens on a clear set relies entirely on the honor system, which is an opportunity that dishonorable individuals can exploit.
Other instances of cheating have included individuals who befriended quizbowl players around the country, then asked for copies of sets that were not yet clear. Tournament directors should exercise great caution in sharing question sets with individuals without the expressed permission of the set's editors and should make sure that staffers who have access to the sets understand that such sets should not be shared before the set is cleared.
Looking things up during a match
Sometimes players will attempt to use outside resources to find the answer to a question as it is being read. In most cases this is done by surreptitiously checking one's phone. It is typically easy to tell when someone is using their phone during a match (which they should not be doing, even for innocuous reasons). Having the scorekeeper keep an eye on players is usually sufficient to curtail suspicious behavior. Also, because quizbowl is often held in classrooms, it is occasionally possible to cheat by reading things off the walls.
Looking at the questions during a round
It is sometimes possible, due to moderator error, to see the text of the questions being read. To avoid this, moderators using paper packets should ensure that they hold them upright with a non-translucent backing sheet, while those using digital packets should make sure that no player has sight lines to the screen.
Biking is a colloquial term for cheating online. It can refer to the specific act of "using Google during questions to look up answers", but is often used to refer to related actions or just cheating in general.
The act of teams colluding during a match to change the outcome is a form of cheating. The most common example of this is a team throwing a match, either to intentionally affect their or the other team's seeding or to benefit the other team. This might include an A team throwing the match to its B team or vice-versa.
Detecting cheating can be difficult, especially if the cheating occurs as a result of obtaining access to questions before a round rather than attempting to illicitly access information during a round. Tournament directors should take great care to ensure that only the TDs have access to the questions before the tournament begins (i.e. do not use a shared team email account for questions if players with access to that email account might be playing in that event). Statistical abnormalities such as unusually high power-to-neg ratios, unusually high spikes in PPG, and a mismatch between tossup points and bonus points may trigger suspicion, but are rarely definitive on their own. During online events, suspicious behaviors observed by either tournament staffers or other teams and players can sometimes provide strong evidence of cheating.
Adjudicating Cheating Accusations
Different events will have different procedures for determining whether or not cheating took place.
The most common consequence of an individual being caught cheating is that they leave the quizbowl community without a backwards glance. This is often the case when the player is relatively new and lacks significant ties to the community.
When an individual is more involved in the community, organizations will often issue bans. In almost every case, the guilty party does not ever try to play another quizbowl tournament and the ban functions as a formality.
Sometimes players who have been accused of cheating stick around. This has been more common in the age of online quizbowl, where there is rarely a smoking gun if someone has been occasionally looking up answers to questions. In some cases, players have had multiple accusations leveled against them - without any way to verify the veracity of these claims, there is no way to determine the level of punishment. The identity of people who have had multiple accusations against them is an example of an open secret, as revealing the name of everyone who is accused of cheating is typically considered inappropriate.
One case of someone who was confirmed to have cheated but still ended up remaining in the community was Eric Mukherjee, who confessed to cheating on roughly ten tossups at the online mirror of Terrapin Open. He received a one-year ban from ACF (effectively meaningless as Eric completed his MD/Ph.D some years ago and will likely never be eligible for ACF tournaments again) and self-imposed a one-year ban on tournaments. Unlike all previous instances of cheating, Eric made attempts to reconcile with the community. He also had a long history of community-oriented work, which (coupled with the relatively minor infraction) many considered sufficient to tip the balances away from a permanent ban.