The aim of the Year in Review is to present an overview of significant developments that occurred in 2023 with notable relevance to international humanitarian law (IHL). Firstly, the Year in Review evaluates armed hostilities that occurred throughout the year in selected states, assessing their legal classification as either international or non-international armed conflicts, belligerent occupation, or situations not meeting the relevant legal criteria for the application of IHL. Secondly, the Year in Review provides a summary of relevant proceedings and developments in the prosecution of serious violations of IHL, such as war crimes, before international, hybrid, and domestic courts and tribunals. Lastly, the Year in Review highlights developments in the fields of arms control and disarmament related to IHL.