CTF (Capture The Flag) is an information security competition in which contestants must exploit a machine or piece of code to extract specified pieces of text that may be hidden in a web page or server known as the flag. It can include a wide range of difficulties, including Reverse Engineering, Networks and Protocols, Programming, Cryptography, Web Security, Exploits, and so on. The goal of all of these puzzles is to capture the flag!
In the subject of information security, Capture The Flag (CTF) is a competition. The main goal is to mimic diverse attack concepts with a variety of challenges, which will gradually open your mind to see things from a different perspective, regardless of which side of the infrastructure you are on.