The subject of computer hacking is vast and deep, allowing for endless exploration and specialism. There is, however, a shared foundation of general knowledge upon which nearly everything depends. At a minimum, a computer hacker should know how to operate a computer and connect to the Internet, as well as how to write software or scripts. A familiarity with internet search engines is also essential. (These topics will be covered in more depth in the The Hacker’s Toolkit.)
It is also useful to study the OSI model and Internet protocol suite (TCP/IP) in order to understand how the Internet works and how systems communicate with each other. TCP and UDP are also worth studying, as they’re the most common network communication protocols currently in use.