ERC-223

ERC-223 is a proposed token standard for fungible tokens on Ethereum, first put forward in 2017 by a developer known as Dexaru. It addresses a flaw in ERC-20: when ERC-20 tokens are sent directly to a smart contract that was not built to handle them, the contract cannot reject them, and the tokens can be stuck permanently. Very large sums have been lost this way over the years. ERC-223 makes a transfer to a contract call a function on the receiving contract, which must accept the tokens or the transfer fails, much as sending ether to a contract works. It also aims to simplify deposits by removing the separate approve-then-transfer steps for many uses. Although the proposal has been discussed and revised for years and some projects have issued ERC-223 tokens, it has not gained the broad support of ERC-20, which remains the dominant standard. Also see ERC-777.