This paper charts the intellectual antecedents of salafi-jihadi thought whilst contextualising it within the broader tradition of salafism. As such, the paper is concerned with thoughts and ideas, and their evolution over time, rather than people, places, or events. This paper adopts the generally accepted understanding of three broad categories within salafism – quietists, politicos, and jihadists – and briefly explains each in turn before offering a detailed exploration of the final one. It is argued that salafi-jihadism is characterised by five essential and irreducible features, which are: jihad (understood in this context as fighting), takfir (excommunication), al-walā’ wa-l-barā’ (love and hate, or loyalty and disavowal for the sake of God), tawḥīd (monotheism), and ḥākimiyya (Islamic governance). Finally, this paper considers the intellectual tensions which exist within the salafi-jihadi movement between theorists and ideologues who seldom find themselves on the battlefield and those who are actually fighting.