The Rig Veda is one of the four canonical texts of Hinduism known as the Vedas.
The Rig Veda Samhita is a collection 1028 hymns and 10600 verses organized into 10 books (also called Mandalas). The hymns are dedicated to various Vedic gods and goddesses.
The Brahmana portion of Rig Veda consists of Aitareya Brahmana (that deals with soma sacrifice) and Kaushitaki Brahmana (discusses other types of sacrifices).
The Aranyakas of Rig Veda are included in the Aitareya Aranyaka and Kaushitaki Aranyaka (same name as the Brahmanas). Aitareya explores the soma sacrifice ritual further, while Aitareya Aranyaks discusses prana (subtle life force) and purusha (individual self).
Aitareya Upanishad and Kaushitaki Upanishad form the Upanishad portion of Rig Veda.
Rig Veda was most likely composed between 1700-1100 B.C.E and later codified during the Kuru Kingdom, perhaps between 1200-900 B.C.E.