This document discusses different types and definitions of hacking. It begins by defining hacking broadly as modifying something to make it work for your purposes. It distinguishes between white hat, ethical hackers who aim to improve security, black hat or cracker hackers who exploit vulnerabilities maliciously, and phreakers who hack telecommunications. The document outlines some famous early hacks throughout history. It provides terminology used in hacking and describes some famous individual hackers as well as hacking groups. Motivations for hacking and modern uses are discussed. Recent harmful hacks are summarized.