Intelligence is a military and/or governmental term referring to the information used in making decisions. Intelligence can be any source of information, suitably assessed and processed according to established methods. Foreign embassies subscribe to the newspapers and keep tabs on the news channels of their host countries — the information doesn't have to be classified to be considered useful intelligence; indeed, so-called OSINT, or open source intelligence, is increasing in both quantity and utility with the ascendancy of digital media. Researchers may also be employed to dig through archives and check facts. An important form of intelligence is so-called "signals intelligence", which attempts to intercept electronic communications and other signals sent between parties working for a hostile, or potentially hostile, entity, or between neutral or even friendly parties but discussing that entity.

In established intelligence agencies, such networks usually follow a linear, rather than distributed, structure, with an agent handler who directs the activities of a number of persons and sources in order to obtain the necessary facts about the target of the intelligence gathering operation. The two main HUMINT agent types used are infiltration and penetration agents. An infiltration agent is someone who enters the target of the operation from the outside, but on a suitable pretext so that they are not suspected of espionage. A penetration agent would already be in place in the target area, and is recruited by the handler, often by means of the MICE principle. The information so gathered is processed by one or more analysts and turned into an intelligence product. Information is conveyed between nodes of the network by a variety of secure/clandestine means, be they physical or electronic.