Rig Veda This veda of praise consists of 1017 hymns (suktas) and
  supplemented by 11 others called valakhilyas. It is divided into 10 books
  or mandalas. The oldest hymns are contained in mandalas II to VII (which
  are also known as the ‘Family Books’ on account of their composition
  being ascribed to certain families of sages, viz. Gritsamada, Visvamitra,
  Vamadeva, Atri, Bharadvaja and Vasishtha), and the latest in mandalas I
  and X. The Rig Veda is the oldest as well as the most important of all the
  Samhitas. Its hymns represent compositions of different periods by
  priestly poets, of various families. It is purely a religious work, and most
  of the hymns are all invocations to the gods. Some hymns specially
  concerned with the danastutis or ‘praises of liberality’ throw light also on
  the political, social and economic aspects of the early Vedic period. It
  represents a stage of development of the human mind in which natural
  phenomena were personified into gods. As a work of art too, it deserves a
  prominent place in world literature. In mandala III, composed by
  Visvamitra, we find the famous Gayatri mantra, addressed to the solar
  deity Savitri.
The Vedic literature consists of two parts: Samhitas and Brahmanas. The
latter itself is divided into three parts: Brahmanas pure and simple, the
Aranyakas, and finally the Upanishads.
They are collections of hymns sung in the praise of various gods. They are
the most essential part of the Vedic literature. They are four in number: Rig
Veda Samhita, Sama Veda Samhita, Yajur Veda Samhita, and Atharva Veda
     The Sama Veda (the name is derived from saman, a song or melody)
consists of 1810, or 1549 if one omits the repetitions, stanzas except 75,
taken from the eighth and ninth mandalas of the Rig Veda and arranged
according to the order in which they were chanted by the udgatri priests at
the soma sacrifice. They were set to tune for the purpose of chanting in this