This edited volume explores the fundamental aspects of the dark web, ranging from the technologies that power it, the cryptocurrencies that drive its markets, the criminalities it facilitates to the methods that investigators can employ to master it as a strand of open source intelligence. The book provides readers with detailed theoretical, technical and practical knowledge including the application of legal frameworks. With this it offers crucial insights for practitioners as well as academics into the multidisciplinary nature of dark web investigations for the identification and interception of illegal content and activities addressing both theoretical and practical issues. Offers a practical and applied dive into the dark web and its technologies, currencies, and criminalities; Provides contributions from academia and practitioners on identifying and monitoring illegal activities conducted on the dark web; Explores state of art in cyber security and cybercrime investigation on a global scale. .