capturetheflag

Capture the flag, commonly abbreviated CTF, denotes two related forms of competition that share a common goal: to obtain a flag. In outdoor play, two teams each guard a base containing a flag and try to infiltrate the opponent's territory, capture their flag, and return it to their own base without being tagged. The game emphasizes strategy, speed, and teamwork, with variations in field size, rules about tagging, and safe zones.

In computing and information security, capture the flag competitions are structured as learning and testing exercises. Teams or individuals solve a mix of challenges to locate or derive "flags," which are strings used to prove a solution. Flags are typically submitted to a scoring system and assigned points. Challenge categories commonly include cryptography, reverse engineering, binary exploitation, web security, forensics, and miscellaneous puzzles. Formats vary: jeopardy-style challenges award points for each solved task, while attack-defense formats require defending one’s own services while attempting to compromise opponents' systems.

History and notable events: The computer security form emerged in the 1990s, with DEF CON's annual CTF helping popularize the format. Since then, many online and offline competitions have appeared, including platforms like CTFtime, picoCTF for education, and university and corporate events that attract participants worldwide.

Impact and organization: CTFs provide practical, hands-on learning in areas such as cryptography, reverse engineering, software security, and incident response. They emphasize problem-solving, collaboration, and time management, and are used for education, skill development, and recruitment within the cybersecurity community.