A token standard is a technical specification for how a class of tokens exposes information and handles operations. Shared methods and events let wallets, exchanges and other applications integrate compatible tokens without inventing a completely different interface for each one.
Different models for different assets
ERC-20 describes fungible token balances, transfers and allowances. ERC-721 tracks individually identified non-fungible tokens. ERC-1155 supports multiple token types and quantities within one contract, including batch transfers. The choice changes how software represents holdings and permissions.
Standards leave room for design
A standard may include mandatory functions and optional extensions. It does not necessarily determine issuance limits, minting authority, upgrade controls, transfer restrictions or the rights represented by a token. Two tokens using the same standard can have very different economic and administrative properties.
Compatibility has boundaries
Supporting a standard does not mean every wallet or venue supports every token that follows it. The blockchain network and contract address still identify the particular asset; a familiar symbol is insufficient. Nor does interface compatibility transfer balances between chains or certify that contract code is safe. Applications must handle the actual implementation and any relevant extensions.