The term "G-Man" originated in the United States in the early 20th century and was used as a slang term for a special agent of the Federal Bureau of Investigation (FBI). The "G" in "G-Man" is generally believed to stand for "Government," as in a government agent. The term became popular during the Prohibition era when FBI agents were tasked with enforcing laws related to the illegal production, transport, and sale of alcohol. Over time, the term "G-Man" has become synonymous with federal law enforcement agents in general, not just those working for the FBI.