With regard to mining crypto for blockchains such as Bitcoin and Ethereum 1.0 that use a proof-of-work (PoW) protocol, validators are people who volunteer a computer to maintain the blockchain's integrity by constantly computing the linkage from the first block to the last. There is generally an abbreviated version of the blockchain that is much smaller than the full chain, which contains every transaction. Validators for a public blockchain are maintained primarily by volunteers, who typically dedicate a computer to the process. There are thousands of validation nodes for a major blockchain such as Bitcoin or Ethereum 1.0.
Ethereum 2.0 (Eth2) Uses a Different Protocol
Ethereum is in the process of changing from proof-of-work (PoW) to proof-of-stake (PoS), and Ethereum miners become Ethereum validators in Eth2.
Validators of all proof-of-stake blockchains, such as Ethereum 2.0, Solana and Cardano, win the right to place the next block of transactions on their respective blockchain based on the amount of native crypto that validators put up as collateral. For example, Ethereum 2.0 validators stake 32 ETH (ether) to participate, and in order to increase their chances of winning the reward, they can set up multiple nodes, each with a stake of 32 ETH. See
Bitcoin,
Ethereum 2.0,
Solana,
Cardano,
blockchain,
crypto miner,
proof-of-stake algorithm and
cryptographic hash function.