Token Standard
A shared set of rules that tokens follow so wallets, exchanges, and other programs can handle them without custom code.
A standard specifies the function names, arguments, and events a token contract must expose, such as reading a balance, transferring units, and announcing a transfer. Without one, every wallet would need bespoke code for every token; with one, a token that has existed for five minutes already works in existing software. On Ethereum standards are published as ERC proposals and become conventions once adopted; other ecosystems have their own, such as SPL on Solana and CW20 in the Cosmos ecosystem. A standard describes an interface and nothing more: a compliant contract can still mint new units, charge a fee on transfer, rebase balances, block addresses, or be upgraded by its owner.
In practice
Because ERC-20 defines a common interface, a newly deployed token appears correctly in wallets and block explorers without any of them being updated first.
The common misunderstanding
Compliance with a standard says only that the contract exposes the expected functions; it is not an audit and does not rule out an owner who can mint, pause, or blocklist.