Pūjā or Poojan is a prayer ritual performed by Hindus to host, honour and worship one or more deities, or to spiritually celebrate an event. Sometimes spelt phonetically as pooja or poojah, it may honour or celebrate the presence of special guest(s), or their memories after they pass away. The word pūjā comes from Sanskrit, and means reverence, honour, homage, adoration, and worship. Puja rituals are also held by Buddhists, Jains and Sikhs.
In Tibetan Buddhism, in which context it is called Guru Puja, takes place at dawn and dusk, chanting scripture passages and taking a common meditation period. From Wikipedia