Every religion in existence today has its fundamental principle embedded in a holy book. For Hindus the Vedas are the ancient scriptures that manifest the code of conduct. Vedas are “Apaurusheya” meaning Super Human and not of human agency. The Vedas were not written by any person but were only heard by Rishis who were the medium between God and Human. That is the reason why Vedas are called Shrutis, meaning Heard. What was heard by the Rishis has been transmitted to the mankind. Sanskrit word Veda has a literary meaning of “Wisdom” or “Knowledge” and regulates the social, legal, domestic and spiritual code of conduct. The literature in Vedas has many maxims that stood the test of time and considered as the torch light that drives the darkness away for the mankind, especially for Hindus. All the other religions of the world claim their authority as being delivered by special messengers of God to certain persons, but the Vedas do not owe their authority to anyone. They are themselves the authority as they are eternal, as they are the Knowledge of the Lord.

It is believed that Sage Bhardwaja did penance with a desire to read and comprehend all the Vedas and Lord Chaturmukha Brahma appeared before him and showed mountain size Vedas and gave the Rishi only three fistfuls of Vedas from the huge pile and along with it also gave a boon of longevity until he finishes reading what was handed over to him. Sage Bharadwaja assumed to be still engaged in reading the same till date. Given the difficulty of reading and comprehending the Vedas, Lord Vishnu incarnated as Krishna Dwaipayana and divided the Vedas into 4 parts for the benefit of the mankind. The four parts of Vedas are: 1)Rig Veda 1) Yajur Veda 3) Sama Veda 4) Adharva Veda.

The Rig Veda: The Book of Mantra

Veda Vyasa initiated the Rigveda to Maharshi Paila. Rigveda has the AyurVeda as sub-veda and Rigveda Purusha has Athreyasa as Gotra, Gayatri Chandassu and Brahma as presiding deity. Charcha, Shravakam,Charchakamu,ShravaneeyaParamu, KramaParamu,Jata, RathaKramamu, Dandakramamu are the parts of Rigveda. It also has Ashwalayani, Sankhyayani, Shakala, Bhaskala and Mandukeya as branches. It starts with the mantra “Agni Meele Purohitam”.
The Rig Veda is the oldest of the Vedas and is the book of Mantra. It houses the oldest form of all the Sanskrit mantras. It is built around a science of sound which comprehends the meaning and power of each letter. Most aspects of Vedic science like the practice of yoga, meditation, mantra and Ayurveda can be found in the Rig Veda and still use many terms that come from it.

The Rig-Veda Samhita is the grandest book of the Hindus, the oldest and the best. It is the Great Indian Bible, which no Hindu would forget to adore from the core of his heart. Its style, the language and the tone are most beautiful and mysterious. Its immortal Mantras embody the greatest truths of existence, and it is perhaps the greatest treasure in all the scriptural literature of the world. Its priest is called the Hotri.
More detailed description of RigVeda can be found at the following link.

The Yajur Veda: The Book of Ritual

Veda Vyasa initiated the YajurVeda to his disciple Vaishampayana. Dhanurveda is the upa-veda of Yajurveda. It has Bhardwajasa Gotra and Thristup Chandassu. Lord Rudra is the presiding deity. Out of 85 branches of this Veda only 18 remain. It explains and expands the procedures of Yagna. Brahana Samhita is the root and it has Shiksa, Kalpamu, Vyakaranamu, Nirukthamu, Jyothishamu and Chandassu as Angas and PrathiPadamu, Anupadamu, Chandassu, Bhasha, Dharamu, Meemamsa, Nyayamu and Tharkamu as Upangas. It starts with the mantra “Ishetva”.

The purpose of the ritual such as Yagnas and Homas is to put together and recreate within ourselves the Cosmic Man or Indra. The ritual is to recreate the universe within our own psyche and thereby unite the individual with the universal. Its series of sacrifices culminate in the Atmayajna or the self-sacrifice wherein the ego is offered up to the Divine. While the lesser sacrifices win the lesser worlds, the Self-sacrifice wins all the worlds and gains the greatest gift of immortality.
The Yajur-Veda Samhita is mostly in prose and is meant to be used by the Adhvaryu, the Yajur-Vedic priest, for superfluous explanations of the rites in sacrifices, supplementing the Rig-Vedic Mantras.

The Sama Veda: The Book of Song

Maharshi Jaimini was blessed with SamaVeda by Veda Vyasa. This Veda has Gandharvam as Upa Veda. Lord Vishnu is the presiding Diety. It has Jagathi Chandassu and Kasyapasa Gotra. This Veda has 1000 branches. It starts with the mantra “ Agni Ayahi”.
The Sama Veda is the Veda of Song. It derives most of hyms from Rigveda but gives a melodious musical chant to the same. Its secret is in its musical annotation and rendering. The Sama Veda represents the ecstasy of spiritual knowledge and the power of devotion. If the Rig Veda is the word, the Sama Veda is the song . The Rig Veda is the knowledge, the Sama Veda its realization. The relationship between both is compared to that of life-partners wherein the SamaVeda plays the husbands role.
The Sama-Veda Samhita is mostly borrowed from the Rig-Vedic Samhita, and is meant to be sung by the Udgatri, the Sama Vedic priest, in sacrifices.

The Atharva Veda: The Book of Spell

Maharshi Sumanta was the disciple who was taught Adharva Veda. The Upa-Veda is Asthra Roopam. Baijanaka Gotra and Lord Indra is the presiding Deity and Thristup Chandassu. It has 9 branches and 5 Kalpas.
The last of the Vedas, this is completely different from the other three Vedas and is next in importance to Rig-Veda with regard to history and sociology. A different spirit pervades this Veda. Its hymns are of a more diverse character than the Rig Veda and are also simpler in language. In fact, many scholars do not consider it part of the Vedas at all. The Atharva Veda consists of spells and charms prevalent at its time, and portrays a clearer picture of the Vedic society.
The Atharva-Veda Samhita is meant to be used by the Brahma, the Atharva-Vedic priest, to correct the mispronunciations and wrong performances that may accidentally be committed by the other three priests of the sacrifice.