OSINT stands for Open Source INTelligence, which can be defined as any publicly available information found on the Internet. OSINT can be collected through a simple browser search (e.g., Google, Firefox) or users can search the deep and dark Web, which is not always readily accessible to the average Internet user.
OSINT can be collected from any public source including online news sites, forums, videos, pastes sites, social media, etc. Any information that is not categorized as "classified" is thus considered OSINT.
Enterprise security teams often use OSINT as a part of their threat intelligence program to get a better understanding of the risks and threats facing the organization. Gathering data from publicly available sources (OSINT) can reveal cyber threat indicators of compromise, which can help companies better prepare for and defend against adversaries.