World Heritage entails the i.e. that certain cultural and natural heritage sites are of outstanding universal value (OUV) and of importance to humanity as a whole and thus its protection is the duty of the international community. This chapter explores the criteria, conditions and factors that determine World Heritage designation, including review of specific categories such as mixed sites, cultural landscapes, serial and transboundary sites. It also explores World Heritage as a socially constructed process, incorporating both consensus and contested interpretations of what constitutes heritage. Understanding heritage as a social construction emerged primarily from the disciplines of human and social sciences and has become widely accepted in cultural heritage theory, particularly for its revealing of the power structures at work in heritage narratives. Cultural heritage conservation has developed into a modern international movement in which organizations such as ICOMOS and UNESCO play an important norm-setting role in defining and updating conservation thought and practice.