The ERC-20 standard, first introduced in 2015, is a protocol for creating fungible tokens on the Ethereum network. There are hundreds of thousands of ERC-20 tokens available. Many tokens on the Ethereum blockchain work differently from one another. ERC-20 addressed this issue by developing standards for token functioning and providing a template for the token generation with the use of an API and smart contract technology. The ERC-20 standard influenced the whole cryptocurrency industry by simplifying token trading over the Ethereum network. Alternative standards, such as the ERC-223, have been proposed to solve apparent problems in the ERC-20 model.