In Buddhism, parinirvana is the final nirvana, the release of the enlightened soul from the cycle of rebirth. The written account of Buddha's parinirvana is one of the most studied texts on life of Siddhartha Guatama. Parinirvana Day is the commemoration of Buddha's death.
Central to Buddhism is the search for complete awakening in order to achieve freedom from suffering and break the cycle of rebirth. Parinirvana is what happens to the enlightened soul upon death. The account of the Buddha's own parinirvana is found in the Mahaparinnibbana Sutta.
On Parinirvana Day, Buddhists read scripture and attend temples, as the BBC describes. People take food, money, clothing and other gifts to monasteries as a form of charity. Buddhists use the day as an opportunity to reflect on their own imminent death as well as the passing of loved ones.