Pitru Paksha or Shradh is a 16-day period in which the Hindus pay homage to their ancestors During this period, the Hindus pay obeisance and offer food to the departed souls of their ancestors. This time period. which begins with the first full moon after Ganesh Chaturthi and ends on the new moon. Shradh can be done for the peace of the ancestors, but the importance of doing Shradha in the Pitru paksha is considered to be of great importance. The shradh is performed on the specific lunar day during the Pitru Paksha when the ancestor—usually a parent or paternal grandparent—died. There are exceptions to the lunar day rule; special days are allotted for people who died in a particular manner or had a certain status in life.
According to legend, when the warrior King Karna died during the Mahabharata war and his soul ascended to heaven, he was given gold ornaments instead of food. Feeling that he cannot keep himself on these things, he addressed Indra of Heaven and asked him why he is not getting real food. Lord Indra then told him that he gave these objects his whole life for charity but never donated food to their ancestors. On which Karna replied that he was not aware of his ancestors: Upon this argument, Indra agreed to return Karna to Earth for a period of fifteen days so that he could cook food in the memory of his ancestors and donate. This period of time is now known as the Pitru paksha.