Pitra Paksh

Pitra Paksh - "pitr(a)" meaning "ancestor(s) - or Śrāddha is a special prayer, in which we pray to our ancestors to show our gratitude and to release any karmic ties.

The ceremony is performed on behalf of all those who have passed away. The Pitra Paksh ceremony is usually performed by relatives to help the Jiva (individual soul) who has cast off his physical body in death. Traditionall the ceremony is performed by the son of the deceased ancestors. A person who has cast off his physical sheath is called a Preta. The part of the Sraddha performed to help him at this stage is called the Preta Kriya.
Gifts to deserving Brahmanas for the benefit of the Pitris (deceased family members), in the proper time and place and with faith, are known as Sraddha. Sraddha gives satisfaction to the Pitris. By the offering of the sixteen Sraddhas, the son helps his anscestors to dwell in joy with the Pitris . 

Sraddha, if performed according to the dharma- sastras, leads to everlasting peace of the departed soul because they are now liberated from karmic bonds and from the cycle of birth and death. This is widely recognized. This is why strict attention is given to the ritual by the ancient seers. Some give a detailed description of the funeral rites and of subsequent rituals at the crematorium or at the home. In the Narad Purana, for example, one finds a description of the sraddha rites as well as qualifications of the brahmana invitee to the rituals. 

The Pitra Paksh ceremony does not take long to complete  - all the mantras and offerings to the devas, rishis and pitris takes between 5 and 10 minutes to perform. The ceremony itself is very simple and few ingredients are required (kussa grass, black sesame seeds, milk, water, purple or white flowers) as well as the FULL names of the deceased ancestors.