Open-source intelligence, or OSINT, is information collected from publicly available sources such as social media posts, profiles, forums, images, news, company websites, and public records. In cyber security, OSINT is a core reconnaissance method because attackers can learn a lot without breaking into anything. They may map identities, habits, locations, workplace details, and relationships from data people share openly.
OSINT matters because small details can combine into a useful target profile. In real attacks, criminals may use public posts, photos, or location tags to identify cryptocurrency holders, choose victims, or craft convincing scams. Defenders use the same technique to assess exposure and spot risky information leaks. Good defense means limiting what is public, reviewing privacy settings, avoiding real-time location sharing, and reducing patterns that link an online persona to a real-world identity.