OSINT, or open source intelligence, is the practice of collecting information from published or otherwise publicly available sources. OSINT operations, whether practiced by IT security pros, malicious hackers, or state-sanctioned intelligence operatives, use advanced techniques to search through the vast haystack of visible data to find the needles they’re looking for to achieve their goals—and learn information that many don’t realize is public. Open source in this context doesn’t refer to the open source software movement, although many OSINT tools are open source; instead, it describes the public nature of the data being analyzed.