'Homams /Havan' are pujas performed for a particular deity by invoking Agni - the God of fire.
A Homa is a sacred fire ceremony in which various forms of the Divine are invoked in a sacred fire that has been kindled according to the guidelines in the Vedic scriptures. Certain special offerings are made into the fire while Sanskrit Mantras are chanted. The combination of the powerful energy of the fire and the Sanskrit mantras creates extremely auspicious and purifying vibrations that are beneficial to all who attend the Homa. The smoke that rises from a Homa contains a powerful healing energy, and as it rises to the heavens it purifies the atmosphere, both physically and subtly, encouraging a peaceful environment and gentle weather. Every kind of negative karma can be purified by the sacred Homa fire, due to divine grace. agni (the elemental energy): Sanskrit word meaning the fire present in all the seven centers. homa (Sanskrit word meaning “offering”): a fire ceremony to achieve a specific Its special element. It is said that when Lord Brahma (the creator among the Trinity) created man, he also created "Homam" for man's livelihood and his attainment of spiritual desires. The fundamental premise of Homam is derived from the Vedams, although, according to "Purusha Sooktham", it is the other way around - Vedams originated from Homam! Anyhow, Vedams and Homam are eternal truths having neither beginning nor end, and are "Apourusheyam" (divine, not the creation of humans). Karmam (work or action) is an integral part of living. Right and wrong Karmams can hardly be discerned by human intellect, and has to be guided by knowledge. Vedams, indeed, contain the highest form of knowledge. The singular goal of Vedam is to guide man through the correct path. And Homam forms the essence of all the Karmams prescribed in the Vedams.

 

The goal of all Homams is the prosperity of the people at large by energizing and protecting the environment. The Sun is considered as the main source of energy supply, and fire is considered as a representation of the Sun's energy. According to the ancient texts on Homam, any offer to Fire as a god, is actually an offer to Sun. Any such offer is either to enrich energy in the environment or to destroy the undesirable elements in the environment, and thus, in both ways, environment is protected. Attaching divine nature to such rituals (like Homam) induced people to practice them. Thus, the ancient texts proclaim that "Such Vaidika Karmams are result-oriented, and meant to lead to Sreyass or spiritual attainments"mental presence is in the navel (food) center.
How Homam is performed?
conducted Each Homam is performed strictly according to scriptures. These are by fully learned and experienced vedic scholars.The ingredients recquired for these homams are different for each homams.Each homam is performed after praying (Shankalpa) for the specific relief / benefit desired for each individual.After each homam, pundits are fed with vedic prayers.
As per our Vedas The 33 Millions Gods Aspect’s Are divided in 3 Parts 11 Millions Devatas are in Water ,11Millions in Fire,and 11Millions in the body of a Priest(Vedic Scholars). Thats the reson in our culture we perform Homam (Havan)Offer Aahuthi in the fire.