This document provides an introduction to hacking competitions called Capture the Flag (CTF) events and the related Cyber Grand Challenge (CGC). It discusses the different types and styles of CTF competitions, including jeopardy and attack-defense styles. It also outlines the problem categories in CTF like reverse engineering, pwnable, cryptography, forensics and web. The document notes the benefits of participating in CTFs and the culture around CTF events. It provides an overview of the CGC, which involves automated systems defending and attacking each other. An example of an automated patching system from the CGC is also summarized.