Yajna is a ritual of sacrifice, practised during the Vedic age by the Hindus, to appease the Gods or the Supreme Spirit Brahmin. Yajna is the outer form of worship in which offerings are made to different deities in a systematic manner, to help the worshipper achieve certain results in life.

Concept of Yajna
The concept lays emphasis on the pouring oblations into the sacrificial fire, while reciting the mantras, so that it directly reaches the Gods. The chanting of mantras is expected to ensure fulfilment of specific desires, the overall welfare of an individual, a group of people or the entire society. Yajna is used on most important occasions, ranging from weddings to the opening of new businesses to graduations to prayers for someone"s health. Some Yajnas are also performed on large scale for the general welfare of the entire community, to increase fertility of soil, to invite rains, to welcome peace and wealth, etc.

Performing of Yajna
Depending upon the degree of complexity, these yajnas may last from a few hours to several days. The number of priests participating and conducting the ceremony would depend upon the nature and objective for which it is performed. The outer aspect of Yajna consists of building an altar, generally with bricks, kindling fire using specific types of grass and wood. A Yajna is typically performed by a Hotar, along with many additional priests chanting Vedic verses. Often there will be a fire in the centre of the Yajna and items are offered into the fire. The offering, which is placed into the fire, consists of several elements, including jav, sesame seeds, rice, ghee, incense and sandalwood. Each element has a different significance. The Yajna, where milk products like ghee or yogurt, fruits, flowers, cloth and money are offered, is also termed "Homa" or "Havan".

Pancha Maha Yajnas
The Hindu tradition has the Pancha Maha Yajnas (Five Great Yajnas) namely:

1. Deva Yajna -consists of offering ahutis to Devas.
2. Pitru Yajna - consists of offering libations to ancestors or pitrus.
3. Bhuta Yajna - consists of offering bali or foodstuffs to all creatures.
4. Manushya Yajna - consists of feeding guests.
5. Brahma Yajna - consists of chanting Vedas, namely Rig Veda, Yajur Veda, Sama Veda and Atharva Veda.

Types of Yajna
There are also the three kinds of Srauta Yajnas, which explicitly describe around 400 yajnas in the Vedas. In the category of ` Nitya Karma` there are 21 sacrifices. There is no compulsion with regard to the rest of the 400 Yajnas. But the 21, included in the 40 Samskaras, are required to be performed at least once in a lifetime of a Dvija. These are divided into groups - Paka Yajnas, Havir Yajnas and Soma Yajnas.

Yajna in Modern Days
It is a fact that the incidence of performing the yajnas and other forms of sacrifices is slowly deteriorating in modern Hindu Society. Hence, today many educated Hindus are not very serious about performing the yajnas and for most of them they are just a part of the tradition, without any significance. The influence of western education, the complexity involved in performing the Yajnas and the decreasing number of priests is the main reasons for it.

However, some devout Hindus still believe in their efficacy and organize Yajnas for various purposes, sometimes in public for a social cause or sometimes in private for a personal gain. Thus, there are yajnas for acquisition of a spouse, childbirth, wealth, removal of obstacles, family happiness and so on.