This important and unique volume begins with seven essays that discuss the contemporary challenges to implementing international humanitarian law. Its second and largest section comprises more than 260 entries covering the vast majority of IHL concepts. Written by a wide range of experts, each entry explains the essential legal parameters of a particular element of IHL, while offering practical examples and, where relevant, historical considerations, and supplying a short bibliography for further research. The starting point for the selection were notions arising from the Geneva Conventions, the Additional Protocols, and other IHL treaties. However, the reader will also encounter entries going beyond the typical scope of IHL, such as those related to the protection of the natural environment and animals, and entries that, in addition to an IHL perspective, discuss relevant issues through the lens of human rights law, refugee law, international criminal law, and so on.