This document provides an overview of the history and nature of international law. It discusses the definition of international law and how it has evolved over time from ancient Rome and the middle ages to the present. Key developments included the 1648 Peace of Westphalia which recognized principles of sovereignty and non-interference, and the 1815 Congress of Vienna which further codified international law. The nature and enforcement of international law is also examined, noting debate around whether it constitutes true "law" given the lack of formal legislature and judiciary, but also arguing states generally recognize and follow international law in their relations.