A technical standard
ERC-20 defines a common interface for fungible tokens on Ethereum. Shared rules allow wallets and applications to interpret basic token functions.
Ethereum as the network
ERC-20 tokens exist within Ethereum and their interactions are recorded on that network. Network fees are commonly called gas and are generally paid in ETH.
A token is not the same as Ether
ETH is Ethereum’s native asset. An ERC-20 token is an asset created through a contract that follows that standard.
Why labels appear
Platforms use network labels to identify technical infrastructure. ERC-20 generally indicates a representation compatible with Ethereum.