Description from cryptocompare.com
Wrapped Bitcoin (WBTC) is the first ERC20 token backed 1:1 with Bitcoin. WBTC standardizes Bitcoin to the ERC20 format, creating smart contracts for Bitcoin. This makes it easier to write smart contracts that integrate Bitcoin transfers.
To receive WBTC, a user requests tokens from a merchant. The merchant then performs the required KYC / AML procedures and verifies the user’s identity. Once this is completed, the user and merchant execute their swap, with Bitcoin from the user transferring to the merchant, and WBTC from the merchant transferring to the user.