A miner is someone or an organization that takes on the task of adding transactions to the blockchain and verifying their validity. They manage computers or networks (nodes) that are part of the blockchain network. Their work includes compiling new transactions into blocks and verifying blocks created by other miners.

As a reward for their efforts, miners not only receive the transaction fees that users pay, but also receive a certain amount of the cryptocurrency (e.g., Bitcoin or Ethereum) that is newly released into circulation. This reward system is an essential part of maintaining and securing many blockchain networks.