What USDT is
A stablecoin is a cryptocurrency that aims to keep a steady value by tracking an external reference. USDT tracks the US dollar: one USDT is meant to be worth one dollar. That peg is what separates it from volatile crypto assets — the point of holding USDT is that it does not move, so it behaves on-chain the way dollars behave in a bank account, transferable over public networks rather than card rails.
The same dollar of USDT can exist on more than one blockchain. Tether issues the token natively on several networks, and the version a person holds depends on which network they received it on. The three that matter for payments are Tron, where USDT follows the TRC-20 token standard; Ethereum, where it follows the ERC-20 standard; and Solana. The dollar value is identical across all three — what differs is the network fee to send it and how quickly a transfer confirms.
Because USDT is a separate issuance from USDC, the two are not the same token even though both target the dollar. They are different stablecoins from different issuers, and a wallet holds them as distinct balances.
What it means in a crypto payment
When a customer says they want to "pay in crypto," they usually mean USDT. It is the most widely held stablecoin and the default unit of account across most exchanges and self-custody wallets, so for many payers it is simply the dollars they keep on-chain. A merchant who accepts USDT is accepting something that behaves like a dollar at the moment of payment, not a position that has to be sold afterward.
The peg also removes the biggest objection to taking crypto: the fear that the coin moves between the quote and the payment. Because USDT tracks the dollar, neither side absorbs a price swing while the customer fetches their wallet and confirms — the amount that was quoted is, near enough, the dollar amount that arrives.
USDT on halfin
halfin accepts USDT on the three networks where Tether has the liquidity that matters for payments — Tron (TRC-20), Ethereum (ERC-20) and Solana — and credits all of them to the same dollar-anchored balance. There is a gate for each of those three and no others; USDT on a chain halfin does not support cannot be accepted, because there is no gate for it.
Invoices are anchored to fiat, so accepting USDT does not require you to reason about the small gap between the USDT/USD rate and an exact dollar. You bill a USD amount; halfin maps it to the payable USDT figure using the live rate and locks that figure when the invoice activates. The customer is shown a concrete amount to send and picks which of the three networks to send it on; your ledger records the dollar amount you billed. Crediting is reorg-aware and waits for the relevant chain's confirmation threshold before the invoice is marked paid. A USDT balance you receive can later be paid out, refunded, or rebalanced into another asset through balance conversion — note that balance conversion is asset-to-asset, not a way to sell USDT for fiat in a bank.