Parinirvana Day, or Nirvana Day is a Mahayana

Mahayana

Mahāyāna is one of the two main existing branches of Buddhism and a term for classification of Buddhist philosophies and practice...

 Buddhist holiday

Holiday

A Holiday is a day designated as having special significance for which individuals, a government, or a religious group have deemed that observance is warranted. It is generally an official or unofficial observance of religious, national, or cultural significance, often accompanied by celebrations...

 celebrated in East Asia

East Asia

East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...

. By some it is celebrated on 8 February, but by most on 15 February. It celebrates the day when the Buddha is said to have achieved Parinirvana

Parinirvana

In Buddhism, parinirvana is the final nirvana, which occurs upon the death of the body of someone who has attained complete awakening...

, or complete Nirvana

Nirvana

Nirvāṇa ; ) is a central concept in Indian religions. In sramanic thought, it is the state of being free from suffering. In Hindu philosophy, it is the union with the Supreme being through moksha...

, upon the death of his physical body. Buddhists celebrate the death of the Buddha because they believe that since he was Enlightened, he was free from the pain of physical existence.

Passages from the Nirvana Sutra

Mahayana Mahaparinirvana Sutra

The Nirvana Sutra or ' ; ; ).) is one of the major sutras of Mahayana Buddhism. It shares its title with another well-known Buddhist scripture, the Mahaparinibbana Sutta of the Pali Canon but is quite different in form and content...

 describing the Buddha's last days of life are often read on Parinirvana Day. Other observances include meditation and visits to Buddhist temples and monasteries. Also, the day is a time to think about one's own future death

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 and on the deaths of loved ones. This thought process reflects the Buddhist teachings on impermanence

Impermanence

Impermanence is one of the essential doctrines or three marks of existence in Buddhism...

.

Some Western Buddhist groups also celebrate Parinirvana Day. Parinirvana day is a very special day and this is respected by many other religions too.