Vesak (from the name of the second month in the Hindu calendar) is the most holy time in the Buddhist calendar. Vesak is also known as Visakah Puja in India, Wesak in Sri Lanka, and as Buddha Purnima in Thailand.

It commemorates the birth, Enlightenment and passing of Gautama Buddha on the one historical day, the first full moon day in May, except in a leap year when the festival is held in June.

It is celebrated throughout Southeast Asia where Theravada Buddhism is prevalent. In Thailand, Buddhists celebrate Vesak with mass releases of caged birds, sacred chants, fasting and other religious observances.