HDG is one of the tokens issued by the Hedge Protocol which enables interest-free lending on the Solana Blockchain. Users are able to deposit collateral and take out USH stablecoin loans. The Hedge Protocol offers vaults with a minimum collateral ratio as low as 110% (90.0% LTV).
USH is a stablecoin pegged to the US dollar that is always redeemable for its underlying value - i.e. users are able to use it to purchase collateral back at any time. However a fee is added on top to ensure redemptions don't happen too often.