The waning phase of the Moon during Hindu Bhaadrapada(Telugu/Kannada lunar) month, which falls around September, is called Mahalaya Paksha or Pitru Paksha. A Paksha is of 15 days. Pitru Paksha is extremely important for Hindus, as a fortnight of revering their ancestors and clearing their Karmic debts. Hindus perform Shraddha (Tithi) during this fortnight. Pitru Paksha/Mahalaya Paksha rituals are compulsorily to be done, as per the right procedures, by every Hindu, annually. The general practice is to perform Shraddha based on the Tithi of the day as, Pratipat Shraddh for those who departed on Pratipat. This continues throughout the entire fortnight. A day is dedicated to women who died as Sumangalis. For these, Shraddh is performed on the ninth day of Pitru Paksha. This is known as Avidhava navami. Shraddh is performed on 13th day (Trayodashi) for children who died. Similarly, Shraddha is performed for those who suffered unnatural death on 14th lunar day. This is known as Ghata Chaturdashi. Mahalaya Sarva-Pitru-Tarpana starts with parents and extends to all relatives who have passed away.
It is interesting to learn that the practice of Pitru Paksha got started by Karna of Maha Bharata. Karna reaches Svarga (the heaven) and is happy. When hungry, he asks the gods for food. He is offered jewellery and gold. When he asks them why this he is not given food, they tell him he did not perform any Shraddh and offer food to his ancestors. Karna says he was not aware who his ancestors were. Karna requests for some time grace to go back to earth and perform Shraddha, he is given fifteen days of grace period. This is the time period that coincides with Pitru Paksha ending in Mahalaya Amavasya. Many more references can be studied in the scriptures about the importance of Pitru Paksha.
In the Shraddha performed year on year, the oblations are offered to gods Vasu, Rudra and Aditya through whom a portion goes to the ancestors of three generations; be it father(Pitru)-grandfather(Pitamah)-great grandfather(Prapitamah) or mother(Matru)-mother’s mother in law(Matahamahi)-mother in law’s mother in law(Prapitamahi). In the Pitru Paksha, all other deceased relatives are also remembered and offered oblations. Even deceased friends are commemorated and offered Tarpan. Even people who are not part of Gotram can offer oblations to their relatives, state the scriptures. In certain cases, the actual dates of demise of their forefathers may not be known to the kartha. In such circumstances, he can offer rituals during the Pitru Paksha, thereby appeasing their souls and obtaining blessings.
Pitru Paksha Shraddh is generally performed in Kshetras that are on the sea-shore and confluence of rivers. The belief is that, divine presence is greater in Kshetras. Pitra Paksha is performed in great masses at Kshetras like Gaya, Gokarna, Rameswaram, Sethukkarai, Varanasi and many others.
The Pitru Paksha rituals greatly relieves the Pitru Dosha(sin). Pitru Dosha causes ill health, misfortunes & lack of peace of mind. Every Hindu with deceased parent(s) must compulsorily perform the Pitru Paksha rituals. The Pitru Paksha/Mahalaya Paksha rituals are extremely important for the wellbeing and long-lasting prosperity of our children and future generations as well. Failing to observe these rituals will lead to Pitru Dosha, thereby resulting in a cascading effect of problems for the future generations.