This work analyzes some of the key lessons learned from the use of the Internet by jihadist groups over the last twenty years: 1) Online activism can be a substitute for commitment to armed jihad. 3) Terrorists are “early adopters” of new technologies, to enjoy spaces of impunity. 4) The investigation of terrorist activities on the Internet becomes increasingly difficult as a result of the adoption of measures of self-protection 5). The terrorist message on the Internet has the capacity to transcend the intentions of its creators.