In the context of cryptocurrencies, mining refers to the computational process of validating transactions and securing the network by solving complex mathematical puzzles. Miners use powerful hardware to compete against each other to complete blocks of transactions, and the first miner to solve the puzzle gets to add the block to the blockchain and is rewarded with newly minted cryptocurrency. This process is integral to the security and functionality of decentralized networks, ensuring that transactions are processed in a trustless environment without a central authority.