Kalki, also called Kalkin,[1] is the prophesied tenth avatar of the Hindu god Vishnu. His birth will end the Kali Yuga, the final of the four eras (Satya Yuga, Treta Yuga, Dvapara Yuga, and Kali Yuga), in the endless cycle of existence within the Sanatan Dharma. This will subsequently start a new cycle with Satya Yuga.
He is described in the Puranas as the avatar who rejuvenates existence by ending the darkest and destructive period to remove adharma and ushering in the Satya Yuga, while riding a white horse with a fiery sword