Shodan, launched in 2009 by John Matherly, is the first search engine for internet-connected devices. Shodan scans the internet to discover and catalog devices, including IoT devices, industrial control systems (ICS), servers, routers, etc. It collects data on IP addresses, open ports, service banners, and software versions, making it a powerful tool for cybersecurity professionals, penetration testers, and researchers. It offers features like Shodan Monitor for real-time network exposure tracking, Shodan Maps for geolocation visualization, and a developer API for programmatic access.