A blockchain cannot exist on its own — it needs participants who will verify transactions, bundle them into blocks, and protect the network from attacks. This task is performed by miners and validators, depending on the consensus algorithm used (PoW or PoS).
Who are miners? (Proof of Work)
Miners operate in blockchains using the Proof of Work (PoW) algorithm — for example, in Bitcoin. Their task is to use computations to find the correct hash for a new block. This requires powerful equipment and a large amount of electricity.
Why is this necessary?
A hash is a cryptographic signature of a block. If the hash is correct, the block is considered valid and added to the chain. This makes forging a block virtually impossible.
Miner reward:
New coins (for example, 6.25 BTC in Bitcoin — decreases over time);
Fees for included transactions.
Role of miners:
Supporting the decentralization of the network;
Confirmation and packaging of transactions;
Protection against attacks, including a 51% attack.
Who are validators? (Proof of Stake)
In PoS networks (for example, Ethereum after the transition to Ethereum 2.0), instead of computations, the stake — the amount of tokens that a validator "freezes" in the system — is important. The larger the stake, the higher the chances of being chosen for validating a new block.
Why is this necessary?
This is an economic incentive: if a validator tries to deceive the system, they lose part or all of their stake (slashing). This motivates honest work.
Validator reward:
Transaction fees;
Sometimes — a small issuance of new tokens.
Role of validators:
Verification of transactions and new blocks;
Maintaining the security of the network;
Participation in voting (in Governance systems).
Why is this important?
Miners and validators are the foundation of trust in blockchain. Without them, the network would cease to be decentralized and secure.
They are like "watchdogs" of the blockchain: ensuring that no one cheats and that every transaction is fair.