This thesis asks why and how terrorist organizations use the Internet to achieve three strategic goals: 1) the dissemination of propaganda, 2) recruitment and 3) fundraising. It is immediately apparent that the Internet offers a number of advantages, including low cost, global reach, and anonymity. Nonetheless, terrorist organizations vary in their exploitation of these advantages according to their immediate objectives. To explain these variations, this thesis presents a comparative study of Al Qaeda, the Islamic State of Iraq and Syria (ISIS), and the Taliban. This study considers how different objectives render distinct narratives and thereby affect how those narratives leverage images and information in the dissemination of propaganda. Similarly, targets of recruitment vary according to the objectives of the respective organizations; this primarily affects their use of social media, including Facebook, YouTube, Twitter, and other applications. Fundraising methods also vary, from local means (extortion, narcotics, smuggling) to contemporary exploitation of digital platforms like PayPal and cell phone applications enabling anonymous donations. This thesis concludes that the sophistication of terrorist organizations online requires an equally sophisticated response that is as essential to the fight against violent extremism as kinetic operations.