Yajña

Yajna (IAST: yajña) literally means "sacrifice, devotion, worship, offering", and refers in Hinduism to any ritual done in front of a sacred fire, often with mantras. Yajna has been a Vedic tradition, described in a layer of Vedic literature called Brahmanas, as well as Yajurveda. The tradition has evolved from offering oblations and libations into sacred fire to symbolic offerings in the presence of sacred fire (Agni).

Yajna rituals-related texts have been called the Karma-kanda (ritual works) portion of the Vedic literature, in contrast to Jnana-kanda (knowledge) portion contained in the Vedic Upanishads. The proper completion of Yajna-like rituals was the focus of Mimansa school of Hindu philosophy. Yajna have continued to play a central role in a Hindu's rites of passage, such as weddings. Modern major Hindu temple ceremonies, Hindu community celebrations, or monastic initiations may also include Yajna vedic rites, or alternatively be based on agamic rituals.

The word yajna (Sanskrit: यज्ञ; yajña or yajJa) appears in the early Vedic literature, composed in 2nd millennium BCE. In Rigveda, Yajurveda and others, it means "worship, devotion to anything, prayer and praise, an act of worship or devotion, a form of offering or oblation, and sacrifice". In post-Vedic literature, the term meant any form of rite, ceremony or devotion with an actual or symbolic offering or effort.

A Yajna included major ceremonial devotions, with or without a sacred fire, sometimes with feasts and community events. It is derived, states Nigal, from the Sanskrit verb yaj, which has a threefold meaning of worship of deities (devapujana), unity (sangatikarana) and charity (dána).

...
Wikipedia