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Puja rituals are also held by Buddhists and Jains. In Hindu practice, puja is done on a variety of occasions, frequency and settings. It may include a daily puja done in the home, or occasional temple ceremonies and annual festivals. In other cases, puja is held to mark a few lifetime events such as birth of a baby or a wedding, or to begin a new venture. The two main areas where puja is performed are in the home and at temples to mark certain stages of life, events or some festivals such as Durga Puja and Lakshmi Puja. Puja is not mandatory in Hinduism. It may be a routine daily affair for some Hindus, periodic ritual for some, and rare for other Hindus. In some temples, various pujas may be performed daily at various times of the day; in other temples, it may be occasional.
Puja varies according to the sect, region, occasion, deity honored, and steps followed. In formal Nigama ceremonies, a fire may be lit in honour of the god Agni, without an idol or image present. In contrast, in Agama ceremonies, an idol or icon or image of a deity is present. In both ceremonies, a lamp (diya) or incense stick may be lit while a prayer is chanted or hymn is sung. Puja is typically performed by a Hindu worshiper alone, though sometimes in the presence of a priest who is well versed in a complex ritual and hymns. In temples and priest-assisted events puja, food, fruits and sweets may be included as sacrificial offerings to the ceremony or deity, which, after the prayers, becomes prasad as food shared by all gathered..
source: https://en.wikipedia.org/wiki/Puja_(Hinduism)