The word Veda would mean Holy knowledge. The other names are Sruti, that which is "heard" and Amnaya, that which came down by tradition. The Vedas are "Apaurusheya", of super-human origin. The Lord ideated from Pranava the Vedas the Rig Veda out of its letter "A", Yajur Veda from the letter "U", Sama Veda from the letter "M" and Atharva Veda from the Ardhamatra. There are four Upa-Vedas viz., Ayurveda, Dhanurveda, Gandharvaveda and Arthasastra. Vedas can be divided into "Karma Kanda" oriented towards attainment of Swarga and "Gjnana Kanda" attainment of immortality. Textually, the Vedas are divided into Mantra portion used for propitiating different deities and the Brahmana portion which are commentaries on the Mantras. Mantras are of different kinds. The first is the Rik type which are made up of Padas or which are composed in metres like Gayatri consisting of 24 syllables, Ushnig 28 syllables, Anushtub 32 syllables. These Mantras when set to Musical scale are called Sama Mantras. Music in the Vedas admits of the seven notes. There is a third category which does not fall under any of the two are the Yajur Mantras. The Brahmanas are also of three varieties: Vidhi, Arthavada and Vedanta Vakyas. Vidhis are those that deal with the nature of Karma, those that explain the results of those Karma and those that speak about the materials used in Karma. The closing portions of the Brahmanas are the Upanishads, of which a 120 are known of which the twelve prominent ones are: Isa, Kena, Katha, Prasna, Mundaka, Mandukya, Taittiriya, Aitareya, Chandogya, Brihadaranyaka, Swetaswatara and Kaushitiki, which set the highest ideal for man.
In the Vedic sacrifices, the Prayoga (operative) Mantras are from the Rigveda, Adhwaryu (priestly) from the Yajurveda and the Audgatra (singing) from the Samaveda. The word Rik means praise from which Rigveda is derived. It consists of 1017 hymns addressed to various Gods grouped in 10 mandalas, each hymn being called a Sukta.There were said to be 21 Sakhas or recensions for this Veda but only six viz Sakala, Bashkala, Ashwalayana, Sankayana, Mandukayana and Aitareya are prevalent now. The Yajurveda is purely devoted to use in rites or rituals. It has two branches: Krishna (Black) and Shukla (White) yajurveda. There were 101 Sakhas for the former and 17 for the latter. In the former, available Sakhas are Taittiriya, Kathaka, Maitrayani and Kapishthala and in the latter Madhyandina and Kanva Sakhas are only available. In the case of Krishna Yajurveda, explanatory portions are included whereas in Shukla Veda consists only of Mantras. The Sama Veda is ritualistic in content and highly poetic in form. Sama Veda had 1000 Sakhas but only three are available Kautuma, Ranayaneeya and Jaimineeya. The Atharva Veda explains for the most part rituals connected with Shantika, Paushtika and Abhicharaka Vidyas i.e. for cure of diseases, gain of wealth etc. This Veda would contain 6000 verses constituting 731 hymns grouped into 20 books. There were 9 Sakhas but only two are available viz Paippalada and Saunaka Sakha.
Sri Veda Vyasa codified the four Vedas and taught them to his disciples Paila, Vaisampayana, Jaimini, Sumantu and his grandson Sukarma. They taught to their disciples and came down to later generations. The five ways of reciting Vedas are 1. Mula 2. Pada 3. Krama 4. Jata and 5. Ghana. In the first Mantras are recited continuously, in the second they are split word by word, in the third the words are joined as 1.2, 2.3, 3.4 etc. In the fourth, again Padas are joined and in textual order and then reverse order and once again in textual order as 1.2, 2.1, 1.2, 2.3, 3.2 etc. In the Ghana, the combinations are most complicated like 184.108.40.206, 220.127.116.11.2.1, 1.2.3 etc are used. These different ways of recitation are said to gain in their potency by so chanting.