Enderûn (Ottoman Turkish: اندرون, from Persian andarûn, "inside") was the term used in the Ottoman Empire to designate the "Interior Service" of the Imperial Court, concerned with the private service of the Ottoman Sultans, as opposed to the state-administrative "Exterior Service" (Birûn). Its name derives from the location of the Sultan's apartments in the inner courts of the Topkapi Palace; its head was the Kapi Agha.