Yajnas and yagas sacrifices offered into the duly consecrated fire occupiedthe central place in Vedic religion. Hence, the need for clear and elaborate instructions to conduct them was keenly felt. And, the Brahmanas fulfilled that need.
The primary content of the Brahmanas can be stated as 'vidhi' or injunctions concerning the various rites and rituals which form a part of the sacrificial system. It comprises such details as: when to perform a sacrifice, which sacrifice for which purpose, who is the person fit to perform it, which are the various components, what are the mantras to be used, where and how, and so on.
Apart from the vidhis, the Brahmanas also contain other topics: hetu, nirukti, stuti or arthavada and akhyana.
Those portions of the work that provide logic and reasoning in support of a vidhi are called 'hetu'. Wherever certain words are explained with their etymological derivations, such statements are termed as 'nirukti'. Stuti or arthavada comprises the statements of praise in support of the injunctions and of derogation, in support of prohibitions. Akhyanas are stories or narration of ancient incidents interspersed in the body of the Brahmana literature. They are often full of esoteric meanings or philosophical speculations.
The Brahmanas occupy a very important place in the Vedic lore. They provided not only the necessary details for the performance of Vedic rites but also the inspiration to sustain them. The various discussions that used to take place during the Brahmana period, concerning the several aspects of the sacrificial religion, gave rise to the Mimamsa system of philosophy.
Each of the four Vedas has its own Brahmanas. Since the number of the extant Brahmanas is rather small compared to what has been mentioned in the grhyasutras and other ancient works, it can safely be surmised that many of them have been lost, perhaps irretrievably.
The Brahmanas available now, may be listed as follows:
Tandya Brahmana, Sadvimsa Brahmana, Samavidhana Brahmana, Arseya Brahmana, Daivata Brahmana, Samhitopanisad Brahmana, Upanisad Brahmana, Vamsa Brahmana and Jaiminiya Brahmana.