The schools of Buddhism are the various institutional and doctrinal divisions of Buddhism, which have often been based on historical sectarianism and the differing teachings and interpretations of specific Buddhist texts. The branching of Buddhism into separate schools has been occurring from ancient times up to the present. The classification and nature of the various doctrinal, philosophical or cultural facets of the schools of Buddhism is vague and has been interpreted in many different ways, often due to the sheer number of different sects, sub-sects, movements, etc. that have made up or currently make up the whole of the Buddhist tradition. The sectarian and conceptual divisions of Buddhist thought are part of the modern framework of Buddhist studies, as well as comparative religion in Asia. Some factors in Buddhist doctrine appear to be consistent across different schools, such as the afterlife, while others vary considerably.