Pitra, or Pitru, refers to the lineage of one's expired ancestors. After death, they are believed to exist in soul form. Hindus perform shradh for their deceased ancestors on the shradh thithi or death anniversary every year or if we do not know that date, Pitra Paksha is the common time for all Hindus to perform shradh for their ancestors together. Yet another date is Amavasya (new moon day) of every month, on which day one can perform shradh.

Hindus perform Shradh to repay the debts we owe to our deceased ancestors and by gratifying their spirits, we will be made free of our sins. It has to be done with full dedication and attention. If it not performed properly, it is believed that people will get pitra dosh.

Pitra Dosh is a big phenomenon in Hindu dharma where people believe that they get the "ancestral curse" or "Pitra Dosh" if our ancestors are unhappy about the shradh we do after they are gone. It may seem weird, but many people believe that they have to make their ancestors happy by performing some rituals and feeding the brahmans after they are dead, otherwise their souls will curse us.