The Vedas explain the process of creation. It says …

Science of Homam
The pure consciousness manifested in the form of space. Then out of space, wind was created. Out of wind, fire was created and out of fire, water was created and out of water, earth was created.

Fire is the subtest element yet perceivable by eyes. So in the Vedic Hindu tradition, fire is used as a medium to invoke the presence of God. In a homa the priest first meditates on the Lord and energizes the space. This energy is transferred to the air element by the chanting of mantras, which in turn energizes the fire in the homa kunda – the sacred fire receptacle. The energy built up in the fire is then transferred to the water in the Kalasas – the water pots kept there. The water when sprinkled or poured on us / on a Deity transfers the whole energy on to the Earth element.

Also the fire is the medium through which the formless energy assumes the form and the matter with the form gets back to its original state of energy. Devi Meenakshi is said to have emerged out of Homa fire. The great saint Tirujnanasambandhar and the great incarnation Vallalar have dissolved their bodies in the yogic fire.

Whatever our prayers can be, they can be manifested into reality through the sacred fire of Homas.

In a typical Homa, a priest invokes the presence of the Deity in the fire through specialized mantras. Since mantras are revealed by Enlightened sages, all mantras carry immense power within them. Once energized, till the end of the homa, the fire itself becomes a deity. Then the Deity is worshipped and several oblations (ahutis) are offered into the fire to create the desired effect. The smoke that emanates from the fire receptacle – homa kunda – energizes the whole space where the homa is done and creates a positive effect in that place.

Homas create a positive effect not only in the people who are around but also in the people whose names have been chanted in the Sankalpa mantra – the mantra for conscious resolution, irrespective of how far they are.

Another very interesting speciality of the way of worship in the Hindu tradition is – like how money is credited in an account which is far away from the place where the money is deposited, homas and pujas done as per the scriptural injunctions create the desired effect in you irrespective of how far you are from the place where the homa /puja is performed.