The Federal Bureau of Investigation (FBI), established in 1908, played a critical role in the 20th-century U.S. as a federal investigative and intelligence agency. Initially focused on crimes like immigration violations and antitrust issues, its scope expanded to include combatting organized crime, espionage, and domestic terrorism, particularly during the Cold War. The FBI also played a key role in civil rights investigations and combating corruption. Throughout its history, the FBI has been involved in significant events, such as the Red Scare, and has continuously evolved to address emerging threats to national security and public safety.