Open Source Intelligence and Human Intelligence deal with using free, online and offline sources to find information, with HUMINT focusing on gathering intelligence FROM people.
HUMINT is contrasted with SIGINT (Signals Intelligence) which deals with intelligence gathering from intercepting communications. The US National Security Agency (NSA) has an in-depth definition of SIGINT.
OSINT focuses on gathering information from sources that are freely available without cost, usually on the Internet.
- https://www.cybertraining.ca/course/osint/ (requires fee, great price though!) - by Ritu Gill at OSINTTechniques.com
- https://www.myosint.training/pages/free-resources by WebBreacher also of #OSINTCurious