There are six basic intelligence sources, or collection disciplines:
- SIGINT—Signals intelligence is derived from signal intercepts comprising — however transmitted — either individually or in combination: all communications intelligence (COMINT), electronic intelligence (ELINT) and foreign instrumentation signals intelligence (FISINT).
- IMINT—Imagery Intelligence includes representations of objects reproduced electronically or by optical means on film, electronic display devices, or other media. Imagery can be derived from visual photography, radar sensors, and electro-optics.
- MASINT—Measurement and Signature Intelligence is information produced by quantitative and qualitative analysis of physical attributes of targets and events to characterize, locate, and identify them. MASINT exploits a variety of phenomenologies, from a variety of sensors and platforms, to support signature development and analysis, to perform technical analysis, and to detect, characterize, locate and identify targets and events. MASINT is derived from specialized, technically-derived measurements of physical phenomenon intrinsic to an object or event and it includes the use of quantitative signatures to interpret the data.
- HUMINT—Human intelligence is derived from human sources. To the public, HUMINT remains synonymous with espionage and clandestine activities; however, most of HUMINT collection is performed by overt collectors such as strategic debriefers and military attaches. It is the oldest method for collecting information, and until the technical revolution of the mid- to late 20th century, it was the primary source of intelligence.
- OSINT—Open-Source Intelligence is publicly available information appearing in print or electronic form including radio, television, newspapers, journals, the Internet, commercial databases, and videos, graphics, and drawings. While open-source collection responsibilities are broadly distributed through the IC, the major collectors are the DNI’s Open Source Center (OSC) and the National Air and Space Intelligence Center (NASIC).
- GEOINT—Geospatial Intelligence is the analysis and visual representation of security related activities on the earth. It is produced through an integration of imagery, imagery intelligence, and geospatial information.
Source: https://www.dni.gov/index.php/what-we-do/what-is-intelligence