Bribery is a crime implying a sum or gift given alters the behavior of the person in ways not consistent with the duties of that person. It is defined by Black's Law Dictionary as the offering, giving, receiving, or soliciting of any item of value to influence the actions as an official or other person in discharge of a public or legal duty. The bribe is the gift bestowed to influence the receiver's conduct. It may be any money, good, right in action, property, preferment, privilege, emolument, object of value, advantage, or any promise or undertaking to induce or influence the action, vote, or influence of a person in an official or public capacity.
It is a form of political corruption and is generally considered unethical. In most jurisdictions it is illegal, or at least cause for sanctions from one's employer or professional organization.
For example, a motorist may bribe a police officer not to issue a ticket for speeding, a citizen seeking paperwork or utility line connections may bribe a functionary for faster service, a construction company may bribe a civil servant to award a contract, or a narcotics smuggler may bribe a judge to lessen criminal penalties.
In some cases, the briber holds a powerful role and controls the transaction; in other cases, a bribe may be effectively extracted from the person paying it.
Expectations of when a monetary transaction is appropriate can also differ: tipping, for example, is considered bribery in some societies, while in others the two concepts may be interchangeable. In Spanish, bribes are referred to as "la mordida" (literally, "the bite"), in middle eastern countries they are Backshish or Bakshish.
The level of non-monetary favours that constitute an incentive to unethical behaviour is variable and may constitute a matter of opinion in a given field:
Payola is the commonplace practice where record companies buy air time from radio and television stations for songs they are promoting.
A grey area may exist when payments to smooth transactions are made. United States law is particularly strict in limiting the ability of businesses to pay for the awarding of contracts by foreign governments; however, the Foreign Corrupt Practices Act contains an exception for "grease payments"; very basically, this allows payments to officials in order to obtain the performance of ministerial acts which they are legally required to do, but may delay in the absence of such payment. In some countries, this practice is the norm, often resulting from a developing nation not having the tax structure to pay civil servants an adequate salary. Nevertheless, most economists regard bribery as a bad thing because it encourages rent seeking behaviour. A state where bribery has become a way of life is a kleptocracy.
Pharmaceutical corporations may seek to reward doctors for heavy prescription of their drugs through gifts. The American Medical Association has published ethical guidelines for gifts from industry which include the tenet that physicians should not accept gifts if they are given in relation to the physician’s prescribing practices.  Doubtful cases include grants for travelling to medical conventions that double as tourist trips.
Dentists often receive samples of home dental care products such as toothpaste, which are of negligible value; somewhat ironically, dentists in a television commercial will often state that they get these samples but pay to use the sponsor's product.
In legal situations, lawyers, judges, and others with power may be subject to bribery or payoff for making a decision that benefits someone willing to pay for favours. Operation Greylord revealed that bribery was rampant in the bench and bar community of Chicago in the early 1980s. In Jagdeo Singh v The State of Trinidad and Tobago (2005) UKPC 35, the Privy Council considered the conviction of a lawyer retained to represent a drug trafficker. It appeared that the client wished the lawyer to secure his release on bail by any means, including the bribery of the magistrate, the prosecutor, and any other public officer who might help.