No topic has gripped the public imagination as dramatically as the spectre of global jihadism. While much has been said about the way jihadists behave, their ideology remains poorly understood. Shiraz Maher, an authority on radicalisation, charts the intellectual underpinnings of Salafi-Jihadism from its origins in the mountains of the Hindu Kush to the jihadist insurgencies of the 1990s and the 9/11 wars.