Yaaga (Yaagam or Yajna) is a Vedic sacrifice or an outer form of ritual worship, in which offerings are made to different deities in a prescribed and systematic manner by worshippers to nourish them and thereby supplicate them, so that they would assist the worshippers in achieving their goals and desires in life. It is usually done with the help of qualified priests. Yaagam leads to Yogam, the auspicious state of harmony and unity with gods and happiness here and hereafter.

Yaagas are usually fire sacrifices and involves the use of ritual or sacrificial fire. Each Yaaga is performed by the host of the sacrifice (Yajamana), his family, one or more attending priests, in the presence of friends, well-wishers and other guests,

The primary purpose of yajnas is to nourish devas. The word deva originally meant gods or light beings. However, in due course it was used to denote, senses, organs in the body, breathe, speech, the mind, king, a Brahmana, a venerable being or a demi-god. Yajnas may be performed to worship any of them. Their primary purpose is to invoke the gods and nourish them.

Their secondary purpose is to harness divine power to fulfill desires, overcome difficulties or achieve the four main goals namely Dharma, Artha, Kama and Moksha. Yajnas may also be performed to discharge karmic debt or uphold Dharma as an obligatory duty. The mantras and hymns which are sung during the sacrifices are meant to appease the gods and help the worshippers to fulfill their desires and seek divine protection.

Yajnas bring gods and humans together to achieve their common goals and participate in God’s eternal duties as active participants in the sacrifice of creation. The source of Yajna is God himself.The Vedas recognize the Yajna as a potent weapon to destroy one's enemies and rivals in love and marriage. In the Yajurveda and Atharvaveda, several Yajnas are suggested to cast spells and delude people. Any Yajna is incomplete unless it reaches the heaven and fulfills its purpose. In that effort, speech, space, the sacred words of the Vedas, the chanting of the mantras, the devotion and sincerity of the worshippers, the purity of the priests, the sanctity of the ritual place and the perfection shown in its performance play an important role.