Modern international humanitarian law is made up of two historical streams: The Law of Geneva and The Law of The Hague International humanitarian law is traditionally seen as distinct from international human rights law (which governs the conduct of a state towards its people), although the two branches of law are complementary and in some ways overlap.

IHL operates on a strict division between rules applicable in international armed conflict and internal armed conflict. There are also other customary unwritten rules of war, many of which were explored at the Nuremberg trials. The law is mandatory for nations bound by the appropriate treaties. Together the jus in bello and jus ad bellum comprise the two strands of the laws of war governing all aspects of international armed conflicts.

It is distinct from jus ad bellum which regulates the conduct of engaging in war or armed conflict and includes the crime of aggression. International humanitarian law, jus in bello, regulates the conduct of forces when engaged in war or armed conflict. Serious violations of international humanitarian law are called war crimes. It is designed to balance humanitarian concerns and military necessity, and subjects warfare to the rule of law by limiting its destructive effect and alleviating human suffering. It defines the conduct and responsibilities of belligerent nations, neutral nations, and individuals engaged in warfare, in relation to each other and to protected persons, usually meaning non-combatants. Sources of international law include international agreements (the Geneva Conventions), customary international law, general principles of nations, and case law. It comprises a set of rules, which is established by treaty or custom and that seeks to protect persons and property/objects that are or may be affected by armed conflict, and it limits the rights of parties to a conflict to use methods and means of warfare of their choice.

International humanitarian law is inspired by considerations of humanity and the mitigation of human suffering. It is a branch of international law that seeks to limit the effects of armed conflict by protecting persons who are not participating in hostilities and by restricting and regulating the means and methods of warfare available to combatants. International humanitarian law ( IHL), also referred to as the laws of armed conflict, is the law that regulates the conduct of war ( jus in bello).

Different types of armed conflict