capture the flag

Capture the Flag (CTF) in computer security is an exercise in which participants attempt to find text strings, called "flags", which are secretly hidden in purposefully-vulnerable programs or websites. They can be used for both competitive or educational purposes. In two main variations of CTFs, participants either steal flags from other participants (attack/defense-style CTFs) or from organizers (jeopardy-style challenges). A combination of those two styles would be called mixed. Competitions can include hiding flags in hardware devices, they can be both online or in-person, and can be advanced or entry-level. The game is inspired by the traditional outdoor sport of the same name.