The representation is the primary source of value that determines the value of USDT. It reflects the USDT peg to the USD, allowing USDT to be used as a stablecoin.
Tether issues and redeems USDT and guarantees one-to-one redeemability. The redemption of USDT directly with the Tether Limited issuer has some additional conditions for USDT holders, such as the imposition of a minimum redemption value (source), KYC/AML procedures and fees.