Define ERC-20.

ERC-20 is a technical standard used for Ethereum-based tokens that defines a common list of rules. This standard outlines the essential functions and events that any token must implement to be considered ERC-20 compliant. These include functions for transferring tokens, querying token balances, and approving the transfer of tokens on behalf of the token owner.

By adhering to the ERC-20 standard, tokens can interact seamlessly with each other and with different applications and exchanges in the Ethereum ecosystem. This ensures compatibility and allows for a wide range of decentralized applications (dApps) to utilize these tokens for various purposes, such as leveraging them for payments, rewards, or governance within different projects.

The other options do not accurately describe ERC-20. For instance, a protocol for Ethereum mining processes pertains to the consensus mechanisms and mining algorithms rather than token standards. Similarly, a type of wallet concerns the storage solutions for tokens, while a platform for buying and selling assets deals with marketplaces rather than the technical specifications governing token creation and transactions.