What is the third book in Vedas?

The third book of the Vedas is called the Atharvaveda. It is a collection of hymns, prayers, and incantations that were used for various purposes, such as healing, protection, and obtaining desired outcomes. The Atharvaveda is considered to be the most diverse of the four Vedas and includes a wide range of topics, including magic, medicine, and music. It is also believed to be the oldest of the Vedas, dating back to around 1200 BCE.