Raksha Bandhan, "the bond of protection", is observed on the full moon of the month of Shravana (August), and it is centred on the relationship between brothers and sisters. Its defining act is simple: a sister ties a rakhi, a sacred thread or ornamented band, around her brother's wrist, applies a mark to his forehead and offers sweets, praying for his wellbeing; in return the brother gives a gift and pledges his protection. The thread stands for a bond of duty and affection, and the festival affirms the mutual obligations of the family.
The custom has expanded well beyond literal siblings. Rakhis are tied between cousins, between friends, and across communities as gestures of solidarity; the reformer and poet Rabindranath Tagore famously used a mass rakhi-tying to protest the 1905 partition of Bengal, turning the thread into a symbol of unity across the Hindu-Muslim divide. A body of legend attaches to the practice, including tales of queens sending rakhis to secure alliances, though these are later embellishments rather than the festival's origin. As a celebration of the sibling bond and of protective loyalty more generally, Raksha Bandhan is one of the most widely kept of the pan-Indian festivals, observed across regions and increasingly in the diaspora.