The four Vedas – Rig, Sama, Yajur, and Atharva – are not the work of any single author. In ancient India, there were many rishis (sages) living simple, contemplative lives in hermitages high in the Himalayas and along the banks of sacred rivers. The rishis had names like Angiras, Bhrigu, Yajnavalkya, and Gargi (Gargi was a woman). They sought to understand the fundamental truths of life – Why are we born? How did the world come into existence? How can we live a good life? Because of their intense inquiry and deep meditation, they received God’s blessings and were able to discover the answers to their profound questions.
God revealed these sacred truths to the ancient sages, and the sages composed hymns and texts in the Sanskrit language to express these truths. Their hymns and texts were then passed on from generation to generation, from teacher to student, by chanting them aloud; they were not yet written down. Eventually, the great rishi, Vyasa, compiled all of their hymns and texts into four collections which are now known as the Vedas.
http://www.hindustudentscouncil.org/index.php?option=com_content&view=article&id=301&catid=73
https://en.wikipedia.org/wiki/Vedas