The ubiquity of computers and the Internet have drastically changed the landscape of crime and deviance. Computer technology enables offenders to anonymously target victims around the world, connect with others who share their interests, and participate in various crimes. The Internet and cellular telephony are increasingly incorporated into real world offenses like prostitution in order to connect sex workers and clients with minimal risk of detection. At the same time, new forms of offending have emerged as a direct consequence of technology, such as computer hacking, which can be used for both beneficial and illegal purposes. The Internet has also become an important environment for extremists and terror groups to communicate their beliefs globally in order to recruit others and generate funds. In light of the increasing adoption of technology, it is critical that researchers explore the complex effects of computer technology on human behavior and the intersection of real world and virtual experiences. Crime On-Line provides detailed criminological explorations of multiple forms of cybercrime, including phishing, hacking, and sex crimes using empirical tests and unique data. This text also includes a comprehensive exploration of cyberterrorism and activism in on-line environments. The law enforcement and policy responses to cybercrimes at the local, state, and federal level are also discussed in detail. This work provides practical policy discussions that will benefit academics, law enforcement, legal counsel, and students at the undergraduate and graduate level.