Rig Veda is the ancient hindu text of Sanatan Dharma. This is also the world's oldest sacred text. There is a collection of 1028 hymns and 10,600 verses where gods are praised in a collection of 10 books. Hindus consider the Vedas to be "apauruṣeya" - not of a man, superhuman.
Vedas are also known as Sruti as they are transferred oraly from one generation to the other and are authorless. They are the heavenly words of the divine and the supreme power - Brahman. In Hinduism, there are four vedas, Rigved, Yajurved, Samaved, Atharvaved. Every Veda has been subclassified into four sacred text group - Samhita, Aranyak, Brahmanas and Upanishads. Samhitas constitutes of mantras and benedictions. Aranyaks constitutes of text on rituals, ceremonies, sacrifices and symbolic-sacrifices. Brahmanas have commentaries on rituals, ceremonies and sacrifices while Upanishads are the text consisting of meditation, spiritualism and philosophy.
Rigved describes about The Creation of the Universe, Nature of God, Virtue of Daan and also covers many Metaphysical Concepts. Rigved constitutes 10 books known as Mandal. Each Mandal has hymns also known as Sukta. In each book, the hymns are arranged in collections, each dealing with a specific deity - Agni comes first, Indra comes second, and so on. Within each collection, the hymns are arranged in the descending order in the number of stanzas per hymn. If two hymns in the same collection have equal number of stanzas then they are arranged so that the number of syllables in the metre are in descending order.
The Rigvedic hymns are dedicated to various deities, chief of whom are Indra, a heroic god praised for having slain his enemy Vrtra; Agni, the sacrificial fire; and Soma, the sacred potion or the plant it is made from. Equally prominent gods are the Adityas or Asura gods Mitra–Varuna and Ushas (the dawn). Also invoked are Savitr, Vishnu, Rudra, Pushan, Brihaspati or Brahmanaspati, as well as deified natural phenomena such as Dyaus Pita (the shining sky, Father Heaven), Prithivi (the earth, Mother Earth), Surya (the sun god), Vayu or Vata (the wind), Apas (the waters), Parjanya (the thunder and rain), Vac (the word), many rivers (notably the Sapta Sindhu, and the Sarasvati River). The Adityas, Vasus, Rudras, Sadhyas, Ashvins, Maruts, Rbhus, and the Vishvadevas ("all-gods") as well as the "thirty-three gods" are the groups of deities mentioned.