Human intelligence (intelligence gathering)

[1] HUMINT can be conducted in a variety of ways, including via espionage, reconnaissance, interrogation, witness interviews, or torture.

[2] NATO defines HUMINT as "a category of intelligence derived from information collected and provided by human sources.

As the name suggests, human intelligence is mostly collected by people and is commonly provided via espionage or some other form of covert surveillance.

The manner in which HUMINT operations are conducted is dictated by both official protocol and the nature of the source of the information.

[4] Surveillance of targets (e.g., military or other establishments, open source or compromised reference documents) sometimes reveals people with potential access to information, but no clear means of approaching them.