Know Your Customer (Client) ... the process of verifying the identity of clients and/or business partners, in order to reduce risks tied to illegal money transactions or other criminal intentions.
In the Crypto space, KYC is used in connection with bank regulations and anti-money laundering laws that intend to control the flow of funds from and to illegal organizations.
Due to this, several levels of verification are required for new clients of pretty much all centralized crypto exchanges.