Open Source Intelligence

Open Source Intelligence (OSINT) is the practice of collecting and analyzing information from publicly available sources — search engines, social media, public records, DNS/WHOIS, image metadata, leaked datasets, and so on — to build a picture of a target. It is used in penetration testing reconnaissance, threat intelligence, investigations, and CTFs, and it relies only on legally accessible data rather than intrusion.

For the list of tools, refer here.