Guru Purnima is celebrated on the full moon day, known as Purnima as per the Hindu calendar of Ashadha month.  The day is celebrated by expressing gratitude and worshipping the spiritual gurus and teachers on this day, thanking for all the knowledge and life-lessons. Guru Purnima Also known as Vyasa Purnima, the day also commemorates the birthday of sage Ved Vyasa, author of several important Hindi texts such as Mahabharata and Puranas.