A validator is a node that proposes and checks new blocks on a Proof of Stake chain. In Proof of Work, miners race to solve puzzles. In Proof of Stake, validators lock tokens as collateral. They are chosen to propose blocks based on stake. Other validators attest. If the attestations check out, the block is added. If a validator proposes or attests to invalid blocks, they lose stake.
That slashing is the penalty. It makes attacks expensive.
Running a validator means keeping a node online, handling keys, and knowing the protocol. On Ethereum, a validator needed 32 ETH to participate. Solo staking is hard for most people. Many join staking pools that combine deposits. That creates centralization risk. If a few pools hold most stake, they can steer the network. Pools are still how most people participate.
Validators earn new issuance plus transaction fees. They profit if the network works. They lose tokens if they cheat. They are the operators of Proof of Stake consensus. This slashing is the punishment mechanism. Solo staking is increasingly difficult. Most validators participate through staking pools where multiple users pool their tokens.
If a few large pools control most staking power, they control the network. On Ethereum, a validator stakes 32 ETH, proposes or attests to blocks, and can be slashed for cheating or going offline too long.
Proof of Stake Validator
Interactive simulation of validator selection, block proposal, and consensus
How it works: Validators are selected based on stake weight. The selected validator proposes a block. Other validators attest to its validity. If 67% attest to a valid block, it's finalized and rewards are distributed.
Slashing: Validators who propose or attest to invalid blocks lose stake and can be banned. Click validators during attestation phase to make them attest.