Cheating is an act of lying, deception, fraud, trickery, imposture, or imposition. Cheating characteristically is employed to create an unfair advantage, usually in one's own interest, and often at the expense of others. Cheating implies the breaking of rules. The term "cheating" is less applicable to the breaking of laws, as illegal activities are referred to by specific legal terminology such as fraud or corruption. Cheating is a primordial economic act: getting more for less, often used when referring to marital infidelity. A person who is guilty of cheating is generally referred to as a cheat (British English), or a cheater (American English).

Sport

see: Doping (sport) Another venue where cheating has occurred is in sport. An implicit agreement exists among participants that they will play by the rules and eschew unfair measures to win. Cheaters violate the rules of competition. Examples include Ben Johnson's disqualification for doping in the 1988 Summer Olympics or the admissions of steroid use by former professional baseball players after they have retired, such as José Canseco and Ken Caminiti..

Cheating refers to more than using illegal substances. Perhaps the most famous example of cheating in professional sport took place in the 1986 FIFA World Cup when Diego Maradona used his hand to punch the ball into the back of the net past the England goalkeeper Peter Shilton. Using the hand or arm by anyone other than a goalkeeper is illegal according to the rules of association football.

Another example of cheating frequently seen in sports is the use of non-regulation (vis-a-vis the rules) equipment. In baseball, a pitcher using a doctored baseball (e.g. putting graphite or Vaseline on the baseball, or a batter using a corked bat are some examples of this.

Circumvention of rules governing conduct and procedures of a sport is also cheating. Erstwhile Indiana University men's basketball coach Kelvin Sampson was ousted from his position for persistent circumvention of rules. Sampson, over a period of 7 years (including his tenure at The University of Oklahoma) circumvented an NCAA rule designed to protect minor student-athletes from incessant interruption of their home lives and studies. The rule forbids college coaches from contacting student-athletes during periods when students are expected to be focusing on school, family life, and high-school team practices. Between his tenure at Oklahoma and Indiana, Sampson evaded this rule over 600 times, thus giving his teams an unfair recruiting advantage over opponents.

Gambling

Cheating in gambling is practiced to gain an unfair advantage over one's opponents or the casino, usually for monetary gain, but also to win wagers having a non-monetary forfeit. In poker and other card games, the cards can be manipulated by a skilled cheater. In casino settings, cards can be counted to predict when cards of a particular denomination are more likely to be dealt, and casinos regard this as an unfair advantage. Other gambling activities such as roulette and craps can give rise to cheating by the use of rigged equipment like loaded dice or rigged roulette wheels.