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An informant (also called an informer) is a person who provides privileged information about a person or organization to an agency. The term is usually used within the law enforcement world, where they are officially known as confidential or criminal informants (CI), and can often refer pejoratively to the supply of information without the consent of the other parties with the intent of malicious, personal or financial gain. However, the term is used in politics, industry and academia.

Informants are commonly found in the world of organized crime. By its very nature, organized crime involves many people who are aware of each other's guilt, in a variety of illegal activities. Quite frequently, confidential informants (or criminal informants) will provide information in order to obtain lenient treatment for themselves and provide information, over an extended period of time, in return for money or for police to overlook their own criminal activities. Quite often, someone will become an informant following their arrest.

Informants are also extremely common in every-day police work, including homicide and narcotics investigations. Any citizen who aids an investigation by offering helpful information to the police is by definition an informant.

The CIA has been criticized for leniency towards drug lords and murderers acting as paid informants, informants being allowed to engage in some crimes so that the potential informant can blend into the criminal environment without suspicion, and wasting billions of dollars on dishonest sources of information.

Informants are often regarded as traitors by their former criminal associates. Whatever the nature of a group, it is likely to feel strong hostility toward any known informers, regard them as threats and inflict punishments ranging from social ostracism through physical abuse and/or death. Informers are therefore generally protected, either by being segregated while in prison or, if they are not incarcerated, relocated under a new identity.

Informants, and especially criminal informants, can be motivated by many reasons. Many informants are not themselves aware of all of their reasons for providing information, but nonetheless do so. Many informants provide information while under stress, duress, emotion and other life factors that can impact the accuracy or veracity of information provided.

Law enforcement officers, prosecutors, defense lawyers, judges and others should be aware of possible motivations so that they can properly approach, assess and verify informants' information.

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Wikipedia