Theravāda (“Doctrine of the Elders”, or “Ancient Doctrine”) is the oldest surviving Buddhist school. It is relatively conservative, and generally closest to early Buddhism. This school is derived from the Vibhajjavāda grouping which emerged amongst the older Sthavira group at the time of the Third Buddhist Council (c. 250 BCE). This school gradually declined on the Indian subcontinent, but its branch in Sri Lanka and South East Asia continues to survive.
The Theravada school bases its practice and doctrine exclusively on the Pāli Canon and its commentaries. After being orally transmitted for a few centuries, its scriptures, the Pali Canon, were finally committed to writing in the last century BCE, in Sri Lanka, at what the Theravada usually reckon as the fourth council. It is also one of the first Buddhist schools to commit the complete set of its canon into writing. The Sutta collections and Vinaya texts of the Pāli Canon (and the corresponding texts in other versions of the Tripitaka), are generally considered by modern scholars to be the earliest Buddhist literature, and they are accepted as authentic in every branch of Buddhism.
Theravāda is primarily practiced today in Sri Lanka, Burma, Laos, Thailand, Cambodia as well as small portions of China, Vietnam, Malaysia and Bangladesh. It has a growing presence in Europe and America.