The festival of Bhai Dooj is celebrated two days after Diwali, and is, like Raksha Bandhan, a day dedicated to the love between a brother and sister. Bhai Dooj is also known as "Bhav-Bij" in Marathi and "Bhai-Tika" in Nepal.
Bhai Dooj is observed primarily in northern India, and on this day sisters pray for the wellbeing and prosperity of their brothers. The rituals performed during the ceremony include sisters putting tika/tilak (vermilion spot) on the forehead of their brother, offering sweets and performing rituals to protect their brother and ward evils, such as taking their 'aarti'. In return the brother offers gifts to their sisters as an expression of love.
Exactly how Bhai Dooj is celebrated differs from one part of the country to another; in Bengal, for instance, sisters often fast through the morning before putting a 'tilak' on the brother’s forehead, and the gifting of rice and new grass is part of the ritual.
In Uttar Pradesh, the brother is gifted with an 'aab'- a length of flax, knotted into a circular shape and dotted with sugar batashas.
In Bihar, an interesting variation of Bhai Dooj starts with the sister cursing her brother, before asking for his forgiveness- for the epithets, as well as for past mistakes.
But no matter how Bhai Dooj is celebrated, it's the spirit of love and togetherness which makes this an important festival.