The Federal Bureau of Investigation (FBI) is a governmental agency belonging to the United States Department of Justice that serves as both a federal criminal investigative body and an internal intelligence agency. Also, it is the government agency responsible for investigating crimes on Indian reservations in the United States under the Major Crimes Act.
The FBI was established in 1908 as the Bureau of Investigation, the BOI or BI for short. Its name was changed to the Federal Bureau of Investigation (FBI) in 1935. The FBI headquarters is the J. Edgar Hoover Building, located in Washington, D.C.
The FBI has investigative jurisdiction over violations of more than 200 categories of federal crime. The FBI is organized into functional branches and the Office of the Director, which contains most administrative offices. An executive assistant director manages each branch. Each branch is then divided into offices and divisions, each headed by an assistant director. The various divisions are further divided into sub-branches, led by deputy assistant directors. Within these sub-branches there are various sections headed by section chiefs. Section chiefs are ranked analogous to special agents in charge.
The FBI can and does at times carry out secret activities overseas, just as the CIA has a limited domestic function; these activities generally require coordination across government agencies.