ERC-777 is a technical standard for token implementation using smart contracts on the Ethereum blockchain. These tokens are similar to ERC-223 tokens in that, unlike ERC-20 tokens, they will not be permanently lost should they accidentally be sent to an unprepared smart contract. Also, like ERC-223 tokens, they are backwards compatible with and retain all the functionality of ERC-20 tokens. ERC-777 tokens are designed to work with ERC-820 smart contracts, which exist as part of a central registry of auditable smart contracts. Because the functionality of these smart contracts can easily be verified, users are able to authorize them to transfer ERC-777 tokens to and from their addresses automatically. Transactions involving ERC-777 tokens can be executed in the same manner as those involving Ether itself: by simply initiating a ‘send’ function. The framework for ERC-777 tokens was first introduced by EIP 777 in November, 2017.