Vesak, also known as Buddha Jayanti, Buddha Purnima, Buddha Day, and Phật Đản, is a holiday traditionally observed by Buddhists in South Asia and Southeast Asia, as well as Tibet and Mongolia. It is the most important Buddhist festival. The festival commemorates the birth, enlightenment (Nibbāna), and passing (Parinirvāna) of Gautama Buddha in Theravada, Tibetan Buddhism and Navayana.