What USDC is
A stablecoin is a cryptocurrency that aims to keep a steady value by tracking an external reference. USDC tracks the US dollar: one USDC is meant to be worth one dollar. That peg is the whole point — unlike a freely floating crypto asset, USDC is built to stay put, so it behaves on-chain the way dollars behave in a bank account, transferable over public networks rather than card rails.
USDC is a fiat-collateralized stablecoin: the tokens in circulation are intended to be backed by reserves, and the issuer aims to keep USDC trading one-to-one with the dollar. The peg is a design target maintained by the issuer and the market, not a guarantee — in practice the live rate sits very close to one dollar and moves only in small amounts around it.
The same dollar of USDC can exist on more than one blockchain. The version a person holds depends on which network they received it on. For payments, the three that matter are Ethereum, where USDC follows the ERC-20 token standard; Base, an Ethereum layer-2 network; 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.
USDC and USDT (Tether) 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 wants to pay on-chain in something that holds its value, USDC is one of the two stablecoins they are most likely to hold. A merchant who accepts USDC is accepting something that behaves like a dollar at the moment of payment — a settlement asset, 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 USDC 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.
USDC on halfin
halfin accepts USDC on the three networks where it has the liquidity that matters for payments — Ethereum (ERC-20), Base 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; USDC on a chain halfin does not support cannot be accepted, because there is no gate for it.
Invoices are anchored to fiat, so accepting USDC does not require you to reason about the small gap between the USDC/USD rate and an exact dollar. You bill a fiat amount; halfin maps it to the payable USDC 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 fiat amount you billed. Crediting is reorg-aware and waits for the relevant chain's confirmation threshold before the invoice is marked paid.
A USDC 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 USDC for fiat in a bank.