This document discusses cyber crime and security. It begins with an introduction that notes the growth of internet usage in Bangladesh but also the rise of cyber crime. It then defines cyber crime as illegal activity committed online using computers and the internet. The document outlines the history of early cyber crimes like spam emails and computer viruses. It identifies two categories of cyber crime: those targeting computers and those using computers as weapons. Several common types of cyber crimes are then defined, including hacking, identity theft, malware, computer vandalism, cyber terrorism, and software piracy. Causes and statistics related to cyber crimes are also mentioned. The document concludes by briefly discussing prevention and security measures.