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- # Validators
-
- Validators are responsible for committing new blocks in the blockchain.
- These validators participate in the consensus protocol by broadcasting
- _votes_ which contain cryptographic signatures signed by each
- validator's private key.
-
- Some Proof-of-Stake consensus algorithms aim to create a "completely"
- decentralized system where all stakeholders (even those who are not
- always available online) participate in the committing of blocks.
- Tendermint has a different approach to block creation. Validators are
- expected to be online, and the set of validators is permissioned/curated
- by some external process. Proof-of-stake is not required, but can be
- implemented on top of Tendermint consensus. That is, validators may be
- required to post collateral on-chain, off-chain, or may not be required
- to post any collateral at all.
-
- Validators have a cryptographic key-pair and an associated amount of
- "voting power". Voting power need not be the same.
-
- ## Becoming a Validator
-
- There are two ways to become validator.
-
- 1. They can be pre-established in the [genesis state](../../tendermint-core/using-tendermint.md#genesis)
- 2. The ABCI app responds to the EndBlock message with changes to the
- existing validator set.
-
- ## Committing a Block
-
- _+2/3 is short for "more than 2/3"_
-
- A block is committed when +2/3 of the validator set sign [precommit
- votes](../spec/blockchain/blockchain.md#vote) for that block at the same `round`.
- The +2/3 set of precommit votes is called a
- [_commit_](../spec/blockchain/blockchain.md#commit). While any +2/3 set of
- precommits for the same block at the same height&round can serve as
- validation, the canonical commit is included in the next block (see
- [LastCommit](../spec/blockchain/blockchain.md#last-commit)).
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