The Federal Bureau of Investigation (FBI) is the principal federal law enforcement agency and domestic intelligence service of the United States. Established on July 26, 1908, it was originally known as the Bureau of Investigation and was renamed in 1935. The FBI's mission focuses on enforcing federal law and protecting national security, with a strong emphasis on preventing terrorism and addressing various forms of crime. The FBI conducts professional investigations and intelligence collection to counter threats from domestic and international terrorists. It also provides criminal justice services to law enforcement agencies at all levels. Key operational divisions include the FBI Laboratory, which examines evidence for criminal cases, the Identification Division, which maintains a national repository for fingerprints, and the FBI National Academy, which offers advanced training for law enforcement professionals. The agency has evolved significantly over the years, particularly under the leadership of J. Edgar Hoover, who implemented important reforms and expanded its jurisdiction.