Guru Nanak Dev Jayanti is a major Sikh festival celebrating the birth anniversary of Guru Nanak, the founder of Sikhism. The festival takes place on the full moon day of the lunar month of Kartik, usually falling in November. Celebrations include devotional singing, readings of the holy scripture (the Guru Granth Sahib), and serving free meals (Langar) to all, emphasizing Sikh values of equality, compassion, and service.