Asalha Puja, also known as Dharma Day, is a significant festival in Theravada Buddhism observed in Thailand on the full moon of the eighth lunar month, typically falling in July. This festival commemorates the first sermon of Buddha, which introduced the Four Noble Truths, the core principles of Buddhism. During Asalha Puja, practitioners engage in listening to sermons and making offerings at temples. It is a public holiday in Thailand, and the day following Asalha Puja marks the beginning of Vassa, a three-month retreat dedicated to meditation, reflection, and prayer. The celebration emphasizes the teachings of Buddha and encourages followers to reflect on the path to nirvana.