Detention generally refers to a state or government holding a person in a particular area (generally called a detention centre), either for interrogation, as punishment for a wrong, or as a precautionary measure while investigating a potential threat posed by that person. The term can also be used in reference to the holding of property, for the same reasons. The process of detainment may or may not have been preceded with arrest. The prisoners in Guantánamo Bay are for example referred to as "detainees".
See more at Wikipedia.org...