International environmental law can generally be described as a subset of public international law. It provides obligations for states including regulating their behaviour in international relations in environmental-related matters. The subject covers concerns affecting the environment generally and globally. These environmental problems may be global, regional, transboundary, national and even local. Problems entail topics such as biodiversity loss, climate change, ozone depletion, toxic and hazardous substances, desertification and deforestation, marine resources pollution, migratory species and air, land and water pollution and issues of natural heritage sites. The goal of this paper is to provide an introductory overview to the study of international environmental law. Its emphasis is on state responsibility and the protection and conservation of the international environment.