More than a decade ago, in 2002, al-Qaeda declared their cyber-aspirations: “We strongly urge Muslim Internet professionals to spread and disseminate news and information about the jihad through e-mail lists, discussion groups and their own Web sites (...). The more Web sites, the better it is for us. We must make the Internet our tool.” Social media is part of today ́s battlefield. Over the past decade the Internet has become increasingly important to the loose and decentralized jihadist movement. This book illustrates that Jihadism online has had tremendous significance within the global jihad movement and no doubt its importance will rise in the future, as improved bandwidth, increased functionality, and the fast growing number of users will make the Internet a far more vital nerve than it is today. Salafi-Jihadist websites and social media spaces legitimate the actions of Islamic terrorists and encourage readers to support the Jihad wherever they can. Social media has offered new ways in which to promote terrorism or Jihad, and thus facilitated its intensification. Today everyone can be a part of a radical movement, anywhere. Due to the availability of propaganda material online, the Internet has not only changed the process of radicalization but influenced the nature of terrorism: the autodidactiv terrorist has become the new threat to Western security services.