Capture the Flag (CTF) is a special kind of security competition where different teams compete to solve security challenges. The core idea is to extract a hidden flag from the challenge and to submit it to the referee to receive points for your team. There are two kinds of CTFs: Jeopardy and attack-defense.
In a Jeopardy-style CTF, the teams independently solve challenges from a list of challenges. For attack-defense CTFs, each team has to reverse engineer a set of services and then attack other teams while defending against attacks at the same time.
CTFs are extremely fun and focus on learning and building security skills in many different areas such as reverse engineering, exploitation, cryptography, forensics, and more.
CTFTime is the go-to hub for everything related to CTFs, where writeups and events are published. Visit it frequently to keep up to date with the CTF community.