This chapter presents the fragmentation of law applicable to targeting in armed conflict, which spans international humanitarian law, international human rights law, and international criminal law. It discusses the interrelationships among these branches of law. Considering IHL’s most direct relevance to targeting in armed conflict, it reviews its material, geographical, temporal, and personal scope. It addresses the foundations of IHL, including the relationship between the principles of humanity and military necessity, as well as the perception of IHL as a regime that authorizes rather than restricts attacks, and also the principle of equality, theoretically designed to ensure implementation of IHL. In the final part of the chapter, the definitions of the central terms used throughout this monograph are discussed – namely that of attack and permissible degree of force to be used against lawful targets – and the restrictions on means and methods of warfare in the same context.