On the fifth day of the bright half of Shravan people worship the snake, or as snakes in India are known, the "nag".

The day is known as "Nag Panchami". The festival falls during the onset of the monsoons and is believed to counter the increased possibility of a snake bite during this time, especially since the rivers are in spate.

People visit temples specially dedicated to snakes and worship them. Shiva temples are also favoured places for veneration as snakes are considered dear to him. In South India, people sculpt images of snakes using cow dung, which are then placed on either side of the entrance to the house. This is done to welcome the snake god. In some other parts of southern India, figures of snakes are drawn with red sandalwood paste on wooden boards, or clay images of snakes coloured yellow or black are purchased. These are then worshipped and offered milk since snakes are believed to like milk. Some go to worship the snake which is believed to be hiding in the holes of anthills. Or else a five hooded snake is made by mixing "gandh" (a fragrant pigment), "halad-kumkum" (turmeric powder), "chandan" (sandal) and "keshar" (saffron) and placed on a metal plate and worshipped.

On this day, devotees pour milk into all the holes in the ground around the house or near the temple to propitiate them. Sometimes, a small pot of milk with some flowers is placed near the holes so that the snakes may drink it. If a snake actually drinks the milk, it is considered to be extremely lucky for the devotee.

Legend has it that the serpents are believed to have the capability to change their shape at will. When in human form, they are depicted as beautiful women and handsome men. The victory of Krishna over the Kaliya snake is commemorated on this day. For this reason Krishna is known as "Kaliya Mardan.

Naga Panchami is observed indifferent ways in different parts of India. One of the oldest festivals, many women fast on this day and in fact it even finds mention in the Puranas. It is believed to be one of the most auspicious days of the entire year. According to the Bhavishya Purana, when men bathe the snakes called Vasuki, Takshaka, Kaliya, Manibhadra, Airavata, Dhritarashtra, Karkotaka and Dhananjaya with milk on the fifth day of the bright fortnight of Shravan, they ensure freedom from danger for their families.

These are then worshipped and offered milk. Snake charmers wander about with all sorts of snakes, to which people offer milk. The snake charmers are paid some money for allowing this Serpent worship developed gradually from the fear of serpents that must have taken a heavy toll on life, particularly at the beginning of the rainy season. In the Ashvalayana Grihyasutra, the Paraskara Grihyasutra and other Grihyasutras, a rite called Sarpabali or 'offerings to serpents' was performed on the full moon night of Shriven. However the reason that it was moved from the full moon night to that of the fifth night of the bright fortnight is not apparent. It may be due to the slight change in the time of the onset of the rains.