Cryptocurrencies are virtual currencies backed by blockchain technology. Each cryptocurrency is either a coin or a token, depending on whether they are hosted on their own native network or another existing blockchain.
- Coins: Cryptocurrencies with their own independent blockchain (e.g., Bitcoin, Ethereum, Cardano).
- Tokens: Cryptocurrencies built on top of another blockchain (e.g., Ethereum-based tokens like ERC-20).
Tokens are widely used in decentralized smart contract ecosystems where developers create platforms, dApps, and tools that require a native token to regulate utility and functionality.
Ethereum dominates as the leading smart contract platform, and interacting with it often introduces users to ERC-20 tokens. But what exactly is ERC-20?
Understanding the ERC-20 Token Standard
ERC-20 (Ethereum Request for Comment 20) is the technical standard for creating fungible tokens on the Ethereum blockchain. It defines a set of rules that all Ethereum-based tokens must follow to ensure compatibility with wallets, exchanges, and dApps.
Why Standardization Matters
Standardized token protocols enable seamless interoperability across the Ethereum ecosystem. ERC-20 ensures:
- Uniform token behavior (e.g., transfers, approvals).
- Simplified integration with third-party services (e.g., MetaMask, Uniswap).
Core Functions of ERC-20 Tokens
Developers implement ERC-20 tokens via smart contracts, which must include these mandatory functions:
| Function | Purpose |
|---|---|
totalSupply | Returns the token’s total circulating supply. |
balanceOf | Checks the token balance of a specific wallet. |
transfer | Sends tokens from one address to another. |
transferFrom | Allows delegated token transfers (e.g., for dApps). |
approve | Authorizes a wallet to spend tokens on the user’s behalf. |
allowance | Returns the number of tokens a dApp can withdraw from a user’s wallet. |
Other Ethereum Token Standards
While ERC-20 is the most widely adopted standard, Ethereum supports specialized token types for unique use cases:
1. ERC-223
- Purpose: Prevents accidental token loss by rejecting transfers to incompatible addresses (e.g., sending ERC-20 tokens to a BEP-20 wallet).
- Advantage: Reduces user errors in cross-chain transactions.
2. ERC-721 (NFT Standard)
- Purpose: Powers non-fungible tokens (NFTs), where each token is unique (e.g., digital art, collectibles).
- Key Difference: Unlike ERC-20, ERC-721 tokens are not interchangeable.
3. ERC-677
- Purpose: Enhances oracle functionality (e.g., Chainlink) by enabling tokens to transmit data and value via the
transferAndCallfunction.
👉 Explore Ethereum token standards in depth
FAQs About ERC-20 Tokens
Q1: Can ERC-20 tokens be mined?
No. ERC-20 tokens are minted via smart contracts and distributed according to predefined rules (e.g., ICOs, staking rewards).
Q2: Are ERC-20 tokens only used for payments?
No. They can represent anything—utility tokens (e.g., Uniswap’s UNI), governance tokens (e.g., AAVE), or even asset-backed tokens (e.g., stablecoins).
Q3: What happens if I send ERC-20 tokens to the wrong network?
The tokens may become irrecoverable. Always verify the network (e.g., Ethereum vs. BSC) before transferring.
Q4: How do ERC-20 tokens differ from Ethereum’s native coin (ETH)?
ETH is Ethereum’s native currency for gas fees, while ERC-20 tokens are third-party assets built atop Ethereum.
👉 Learn how to securely store ERC-20 tokens
Key Takeaways
- ERC-20 is the backbone of Ethereum’s token economy, enabling standardized, interoperable assets.
- Specialized standards like ERC-721 (NFTs) and ERC-677 (oracles) cater to niche applications.
- Always double-check wallet addresses and networks to avoid token loss.
By understanding these standards, users and developers can navigate Ethereum’s ecosystem with confidence.