This is a list of intelligence gathering disciplines.
Human intelligence—gathered from a person on the ground.
Espionage
Friendly accredited diplomats
Military attachés
Non-governmental organizations (NGOs)
Patrolling (Military police, patrols, etc.)
Prisoners of war (POWs) or detainees
Refugees
Strategic reconnaissance, as by special forces
Traveler debriefing (e.g., CIA Domestic Contact Service)
Geospatial intelligence—gathered from satellite, aerial photography, mapping/terrain data
IMINT—Imagery intelligence: gathered from satellite and aerial photography
Measurement and signature intelligence:
Electro-optical MASINT
Airborne Electro-Optical Missile Tracking MASINT
Tactical Countermortar Sensors
Infrared MASINT
Optical Measurement of Nuclear Explosions
LASER MASINT
Spectroscopic MASINT
Hyperspectral Imagery MASINT
Space-based Staring Infrared Sensors
Nuclear MASINT
Radiation survey and dosimetry
Space-based Nuclear Energy Detection
Effects of Ionizing Radiation on materials
Geophysical MASINT
Weather and Sea Intelligence MASINT
Acoustic MASINT (also known as ACOUSTINT or ACINT - Acoustic phenomena)
Seismic MASINT
Magnetic MASINT
Gravitimetric MASINT
Radar MASINT
Line-of-Sight Radar MASINT
Synthetic aperture radar (SAR) and Inverse Synthetic Aperture Radar (ISAR) MASINT
Non-Cooperative Target Recognition
Multistatic Radar MASINT
Passive Covert Radar
Materials MASINT
Chemical Materials MASINT
Biological Materials MASINT
Nuclear test analysis
Radiofrequency MASINT
Frequency Domain MASINT
Electromagnetic Pulse MASINT
Unintentional Radiation MASINT
Open-source intelligence—gathered from open sources.
Can be further segmented by source type; Internet/General, Scientific/Technical and various HUMINT specialties (e.g. trade shows, association meetings, interviews, etc.)
Signals intelligence—gathered from interception of signals
COMINT—Communications Intelligence
ELINT—Electronic Intelligence: gathered from electronic signals that do not contain speech or text (which are considered COMINT).
FISINT—Foreign Instrumentation Signals Intelligence, was formerly known as TELINT or Telemetry Intelligence. TELINT, entails the collection and analysis of telemetry data from the target's missile or sometimes from aircraft tests.
Technical intelligence—gathered from analysis of weapons and equipment used by the armed forces of foreign nations, or environmental conditions.
MEDINT—Medical intelligence: gathered from analysis of medical records and/or actual physiological examinations to determine health and/or particular ailments/allergetic conditions for consideration.
Cyber Intelligence/Digital Network Intelligence—gathered from cyberspace
Financial intelligence—gathered from analysis of monetary transactions
