The Internet has long been a favorite tool for terrorists. Terrorists use the Net to expand the reach of their propaganda to a global audience, to recruit adherents, to communicate with international supporters and ethnic Diasporas, to solicit donations, and to foster public awareness and sympathy for their causes. About 90% of terrorist activity on the Internet is using social networking tools, be it independent bulletin boards, Paltalk, or Yahoo! eGroups. These forums act as a virtual firewall to safeguard the identities of those who participate, and they offer surfers an easy access to terrorist material, to ask questions, and even to contribute and help out the Cyber jihad. This chapter examines the current use of interactive online communication by terrorists and their supporters.