This chapter critically analyses the impact of the Internet and associated technology on the rise in terrorist attacks across the US and Europe over the last two decades. To this end, the chapter will be focusing on jihadists’ use of the Internet, yet comparisons will also be made with the radical right. Although there exist certainly differences between the groups, there are also similarities between them, and, in turn, this chapter will address these movements as a collective. The jihadist terrorist organisations that will be analysed in this chapter will include Al-Qaeda and ISIS. The findings reveal that although the Internet has been linked to the preparation and execution of attacks, as this chapter will explore, it is difficult to establish direct cause and effect associations between the Internet and the rise in attacks in Europe and the US.