On Ethereum, most issued assets—USDT, DAI, WETH, and many DeFi tokens—live as ERC-20 contracts rather than as native chain currency. For readers who need to separate the token standard from network choice and fees, the coverage includes how ERC-20 works with smart contracts, how it differs from TRC-20, how to transfer and verify transactions, and which risks matter most in everyday use.
Key Takeaways
- ERC-20 (EIP-20) is Ethereum’s main fungible token interface; compliant contracts expose the same core methods so wallets and apps stay interoperable.
- Sending ERC-20 tokens always uses the Ethereum network and requires ETH for gas—even when the asset being moved is USDT or another token.
- USDT ERC-20 and USDT TRC-20 are different network versions: Ethereum uses
0x… addresses and ETH fees; TRON uses T… addresses and TRX fees.
- Before trading or approving a token, verify the contract on Etherscan and review spending allowances—wrong network or unlimited approvals are common loss paths.
What Is ERC-20?
ERC-20 is a technical standard for fungible tokens created by smart contracts on the Ethereum blockchain. “ERC” stands for Ethereum Request for Comments; “20” is the proposal number. Fabian Vogelsteller introduced it as an Ethereum Improvement Proposal (EIP-20) in November 2015, and the community adopted it widely after finalization in 2017.
Because every compliant token implements the same interface, wallets, exchanges, and other contracts can perform the same standard interactions—checking balances, moving tokens, and granting allowances—without custom code for each project. That shared blueprint is why ERC-20 became the default format for ICO-era launches and remains the backbone of Ethereum DeFi liquidity, governance tokens, and many stablecoins.
ERC-20 tokens are fungible: one unit is interchangeable with another of the same contract, similar to how one US dollar equals another. ETH is the native cryptocurrency of Ethereum and does not implement the ERC-20 interface; wrapped versions such as WETH exist so ETH can behave like an ERC-20 inside DeFi protocols. Not all tokens are currencies—some represent voting rights, rewards, or other digital assets. For the official method list and events, see the ERC-20 documentation on ethereum.org and EIP-20.
How Do ERC-20 Tokens Work?
An ERC-20 token is created on Ethereum through a token contract, not on its own blockchain. Balances and transfers are recorded inside that contract. When a user sends tokens, the wallet calls functions such as transfer or transferFrom to move tokens and update the account balance at a specified address, and validators include that call in a block.
Three practical rules follow from that design:
- Network is always Ethereum for ERC-20 transfers—selecting the wrong chain on an exchange can strand funds.
- Addresses start with
0x…—the same format as an ETH address; one Ethereum address can hold ETH and many ERC-20 balances.
- Gas is paid in ETH—the token contract moves token balances, but the network fee is still settled in ETH, so a wallet needs a small ETH buffer even to move USDT.
Optional metadata fields—name, symbol, and decimals (often 18 decimal places)—help wallets display balances. totalSupply reports the total supply the contract currently tracks; issuers may mint or burn depending on design, and projects can add additional functionality on top of the base standard, so “fixed supply forever” is a project choice, not a hard ERC-20 requirement.
What Functions Does the ERC-20 Standard Require?
ERC-20 defines six key functions plus optional metadata. Together they let apps read balances, transfer tokens, and let a third party spend on a user’s behalf.
Figure 1. Overview of common ERC-20 contract functions.
| Function |
Role |
totalSupply |
Returns the total token amount tracked by the contract |
balanceOf |
Returns the token balance of an account at a specified address |
transfer |
Moves tokens from the caller to another address |
approve |
Authorizes a spender (wallet, DEX router, or contract) to use up to a set amount from the owner's account |
allowance |
Returns the current allowance a spender may still use for an owner |
transferFrom |
Lets an approved spender move tokens from the owner to a recipient |
approve + transferFrom is the pattern DeFi uses for swaps and deposits: the user first grants allowance, then the protocol pulls tokens. That convenience is also a risk surface—unlimited allowances can let a malicious or compromised contract drain a wallet if left unchecked, so many interfaces encourage resetting approvals before changing them. The Transfer and Approval events log these actions for explorers and indexers.
How Does USDT ERC-20 Differ From USDT TRC-20?
Tether (USDT) is issued on multiple chains. ERC-20 USDT lives on Ethereum; TRC-20 USDT lives on TRON. They share a ticker but are not interchangeable on-chain—you cannot send USDT from an Ethereum address directly to a TRON address.
| Feature |
USDT ERC-20 |
USDT TRC-20 |
| Blockchain |
Ethereum |
TRON |
| Fee token |
ETH |
TRX |
| Typical fee level |
Higher during congestion |
Usually lower |
| Confirmation feel |
Minutes depending on gas |
Often seconds to minutes |
| Address format |
Starts with 0x… |
Starts with T… |
| Best fit |
Ethereum DeFi and ERC-20 wallets |
Low-cost transfers when both sides support TRON |
Choose ERC-20 when the destination is an Ethereum wallet, DEX, or DeFi app. Choose TRC-20 when both the sender and receiver explicitly support TRON and fee savings matter more than Ethereum ecosystem access. Always match the network label on both sides of a transfer.
How Do You Transfer ERC-20 Tokens and Check Them on Etherscan?
Compatible wallets such as MetaMask and many exchange deposit pages support ERC-20 assets. A typical send flow:
- Confirm the wallet holds enough ETH for gas, plus the ERC-20 amount to send.
- Select the token, paste a recipient
0x… address that supports Ethereum, and verify network = Ethereum / ERC-20.
- Review the estimated gas fee (speed tiers change gwei and total ETH cost), then confirm.
- Save the transaction hash (TxID) from the wallet or exchange.
To verify status on Etherscan:
- Paste the TxID into the search bar.
- Check status (
Success / Pending / Failed), from/to addresses, token amount, and confirmation count.
- For the token itself, open the contract page and confirm the verified contract name and official links before buying or approving.
Cross-chain moves (for example ERC-20 USDT to TRC-20 USDT) require an exchange or bridge that supports both networks—not a direct wallet send. Wrong-network deposits are a leading cause of lost stablecoins.
What Are the Pros and Risks of Using ERC-20?
Advantages
- Wide wallet and exchange support through a universal set of rules across wallets, decentralized exchanges, and other tokens
- Faster project launches because teams can issue their own tokens without reinventing token plumbing
- Deep DeFi composability—decentralized finance depends on ERC-20 interoperability for liquidity pools, lending, and bridges
- Transparent balances and transfers readable on public explorers
Risks and limits
- Gas paid in ETH can spike when Ethereum is congested, making small transfers uneconomical
- Sending tokens to the wrong network or an incompatible contract can make funds unrecoverable
- Phishing sites and fake contracts mimic popular tickers; always verify the contract address
- Unlimited
approve allowances increase drain risk if a spender is malicious or exploited
- Pure ERC-20 has no built-in hooks when tokens are transferred into contracts that cannot handle them—funds can get stuck without rescue logic
Basic crypto wallet security habits apply: store seed phrases offline, check dApp URLs, verify contracts on Etherscan, and revoke unused allowances periodically.
Summary
ERC-20 is one of the most important Ethereum Improvement Proposals and remains Ethereum’s dominant fungible token standard: a shared smart-contract interface for fungible assets across wallets, exchanges, and DeFi. Native ETH remains the fee currency; ERC-20 balances live in contracts behind 0x… addresses. Comparing USDT ERC-20 with TRC-20, transferring carefully, checking TxIDs on Etherscan, and managing approvals are the practical skills that matter more than memorizing function names alone. Newer standards such as ERC-721 for NFT assets solve different problems, but ERC-20 remains the default for fungible crypto on Ethereum.
FAQ
What is an ERC-20 token?
An ERC-20 token is a fungible digital asset issued by a smart contract on Ethereum that implements the ERC-20 interface. Wallets and apps interact with it through standard methods such as balanceOf, transfer, and approve.
Is ETH an ERC-20 token?
No. ETH is Ethereum’s native currency and pays gas. WETH and similar wrapped forms are ERC-20 representations of ETH used inside token-based protocols.
What is the difference between ERC-20 and TRC-20?
ERC-20 runs on Ethereum with 0x… addresses and ETH fees. TRC-20 runs on TRON with T… addresses and TRX fees. Same ticker assets (such as USDT) on each network are separate and must not be mixed in a single transfer.
Why do I need ETH to send USDT ERC-20?
USDT ERC-20 transfers are Ethereum transactions. The token contract updates balances, but the network still charges gas in ETH, so the sending address needs enough ETH to cover the fee.
How can I check an ERC-20 transaction?
Copy the TxID from your wallet or exchange, search it on Etherscan, and confirm status, addresses, token amount, and confirmations. For new tokens, also open the contract page and verify the published address before interacting.
