The primary objective of the authors of this publication is to understand the efficacy of terrorists use of the Internet and the scope of this activity, and to analyze the content, graphics and source code. Topics covered include the use of the Internet for psychological warfare in general and for terrorist narrow-casting to specific audiences. The discussion focused in particular on the Global Jihad. Terrorist websites were analyzed in terms of common graphical and linguistic motifs. Different methodologies for targeting different audiences were discussed, including the increasing outreach on the part of extremist groups to young children in both Muslim countries and the West. Readers can learn how online communities evolve, and how membership in an online community can promote isolation and radicalization, particularly among immigrant societies. The psychological side of these communities was also dealt with, including extremists manipulation of the younger members of immigrant communities. The ultimate goal of this publication is not only to evaluate the effectiveness of terrorist propaganda on the web and its influence on the target audience, but to recommend practical steps that can be taken to counter this effectiveness. This includes the exploitation of vulnerabilities resulting from jihadists behavior online, and the analysis of jihadist forums and websites for intelligence gathering.