This report hopes to contribute to developing research in the ever-evolving arena of radicalisation with a particular focus on the role of the Internet. Our aim is to provide a resource for both policy makers and practitioners that offers an in-depth insight into the means by which extremists use online tools to propagandise and recruit. While previous research has focussed on specific aspects of this phenomenon, this report aims to provide a comprehensive analysis encompassing both qualitative and quantitative methods. It is also unique in that it offers a detailed and practical guide on how to turn the tide against extremists online and reclaim the Internet. Our research would not have been possible without the cooperation and assistance of colleagues, experts, mentors and focus group participants. In particular, we would like to thank our research assistants Ariana Skipp and Aimee Gentry who diligently collected data transcribed interviews and proofread drafts. We would also like to thank Jonathan Russell, Usama Hasan, Faisal Ghazi, Verity Harding, Florian Maganza and Benoit Tabaka for their support, assistance and guidance.