OSINT, or Open-Source Intelligence, is the practice of collecting, analyzing, and interpreting information from publicly available sources to produce actionable intelligence, used by governments, businesses, and security professionals for national security, competitive analysis, and cybersecurity. It involves gathering data from the internet (social media, news, public records), media (broadcast, print), and other public records, transforming raw data into valuable insights for decision-making, and is crucial for threat hunting, vulnerability assessment, and understanding adversaries.