A token standard is a contract interface: a fixed set of rules — how to check a balance, how to move tokens, how transfers are announced — that every token on that chain follows. Because USDT follows each chain's standard, any compatible wallet can hold it without custom code.
ERC-20: Ethereum's standard
ERC-20 defines transfer, balanceOf, approve/transferFrom and the Transfer event log. Nearly every EVM chain reuses it, which is why your Ethereum private key controls the same address on BSC, Polygon, Arbitrum and Optimism. USDT's ERC-20 contract is one of the most-called contracts in existence.
TRC-20: Tron's equivalent
Tron's TRC-20 mirrors ERC-20 almost one-to-one but runs on a delegated-proof-of-stake chain with 3-second blocks and a resource model (bandwidth + energy) instead of gas. Its killer feature is cost: TRC-20 USDT transfers settled around $1 trillion in annual volume precisely because moving value is cheap and fast.
BEP-20: BNB Chain's flavor
BEP-20 is ERC-20-compatible with one quirk you must know: USDT on BEP-20 uses 18 decimals while ERC-20 USDT uses 6. The same "1 USDT" is 1000000 base units on Ethereum but 1000000000000000000 on BNB Chain. Mixing them up in code or a manual transfer is a classic bug.
Why standards matter to you
- Interoperability: one wallet standard supports every token on that chain.
- Safety: explorers, portfolio trackers and tax tools understand standard events automatically.
- Composability: DeFi protocols list USDT once per standard, not once per project.
See the glossary for token standard, decimals and contract definitions.
