Police stings, also known as undercover operations, are a type of law enforcement tactic used to catch criminals in the act. A police sting typically involves a law enforcement officer posing as someone else in order to gain information or evidence from a suspect. Traps and setups are two common types of police stings. A trap is a situation that is designed to catch a person in the act of committing a crime. Setups involve law enforcement officers setting up a situation in which they can observe a suspect's behavior and gather evidence.