ERC-20 is a technical standard used for smart contracts on the Ethereum blockchain. It defines a set of rules that must be followed by Ethereum tokens in order to be compatible with the Ethereum platform.

ERC-20 tokens are digital assets that are built on top of the Ethereum blockchain and can be transferred and stored like any other cryptocurrency. However, unlike cryptocurrencies like Bitcoin and Ethereum, which have their own independent blockchain, ERC-20 tokens are built on top of the Ethereum blockchain and rely on Ethereum’s infrastructure to function.

The ERC-20 standard was introduced in 2015 and has become the most widely-used standard for creating tokens on the Ethereum platform. It defines a set of six functions that must be implemented by any ERC-20 token, including functions for transferring tokens, checking the balance of an account, and approving other accounts to transfer tokens on behalf of the owner.

ERC-20 tokens have gained popularity because they are easy to create and can be easily integrated into a variety of different applications and platforms. They have been used for a wide range of purposes, including fundraising, voting systems, and loyalty programs.

While the ERC-20 standard has been widely adopted and has become the de facto standard for creating tokens on the Ethereum platform, it has also faced some criticism. Some have argued that the standard is too rigid and inflexible and that it may not be suitable for all types of tokens and use cases. Despite this, the ERC-20 standard remains the most widely-used standard for creating tokens on Ethereum and is likely to continue to play a significant role in the cryptocurrency industry.