Why we celebrate
Mahalaya Amavasya is the day of honouring ancestors (pitrs) with tarpan and offerings, beginning the Durga Puja season.
Pitru Paksha tradition
When
Mahalaya Amavasya falls on the new moon of the month of Ashwin (September-October).
Since when it is followed
The Pitru Paksha and Mahalaya observance is ancient.
Ancient tradition
Who celebrates / for whom
Celebrated by Hindus who perform Shraddha for their ancestors, especially in Bengal before Durga Puja.
Origin
The origin is the fortnight of Pitru Paksha, when the ancestors are honoured, and the beginning of the Durga Puja season.
Shraddha tradition
Key deities
The ancestors (pitrs), and in Bengal the invocation of Durga begins on this day.
How to celebrate
Offer tarpan (water libations) to the ancestors, perform shraddha, and give charity.
Rituals & offerings
Tarpan, shraddha, pind daan, and the offering of food and water to the ancestors.