ERC-20 tokens are digital tokens that exist on the Ethereum blockchain. One of the standout features of Ethereum is its ability to support smart contracts. Smart contracts are programs which control a specific amount value and automatically distribute this value based on specific events. ERC-20 tokens represent value within a smart contract and are created using a smart contract. Many popular cryptoassets that exist today are ERC-20 tokens which are designed to serve a specific purpose. A list of these tokens can be found at https://eidoo.io/erc20-tokens-list/ .