There are four Vedas: the Rigveda, the Yajurveda, the Samaveda and the Atharvaveda. Each Veda has been subclassified into four major text types - the Samhitas (mantras and benedictions), the Aranyakas (text on rituals, ceremonies, sacrifices, and symbolic-sacrifices), the Brahmanas (commentaries on rituals, ceremonies, and sacrifices), and the Upanishads (texts discussing meditation, philosophy and spiritual knowledge). Some scholars add a fifth category – the Upasanas (worship).
The Yajurveda (yajurveda, from yajus meaning "prose mantra" and Veda meaning "knowledge") is the Veda of prose mantras. An ancient Vedic Sanskrit text, it is a compilation of ritual offering formulas that were said by a priest while an individual performed ritual actions such as those before the yajna fire. Yajurveda is one of the four Vedas, and one of the scriptures of Hinduism. The exact century of Yajurveda's composition is unknown and estimated by scholars to be around 1200 to 1000 BCE, contemporaneous with Samaveda and Atharvaveda.
The Gayatri Mantra, also known as the Savitri mantra, is a highly revered mantra from the Rig Veda (Mandala 3.62.10), dedicated to Savitr, the Sun deity. Gayatri is the name of the Vedic meter in which the verse is composed. Its recitation is traditionally preceded by oṃ and the formula bhūr bhuvaḥ svaḥ, known as the mahavyahrti, or "great (mystical) utterance". Vishvamitra is said to have created Gayatri Mantra.