# Proof of Authority (PoA)

Clisha Chain implements the QBFT, proof of authority (PoA) [consensus protocols](https://github.com/ClishaChain/docs/blob/main/docs/besu/how-to/configure/consensus/index.md). PoA consensus protocols work when participants know each other and there is a level of trust between them.

PoA consensus protocols have faster block times and a much greater transaction throughput than the Ethash proof of work consensus protocol used on the Ethereum Mainnet.

In QBFT, a group of nodes in the network act as validators. The existing nodes in the signer/validator pool vote to add nodes to or remove nodes from the pool.

## Properties

* Immediate finality.
* Minimum number of validators.
* Liveness.
* Speed.

### Immediate finality

QBFT has immediate finality; there are no forks and all valid blocks get included in the main chain.

### Minimum number of validators

To be Byzantine fault tolerant, QBFT requires a minimum of four validators.

### Liveness

QBFT networks require greater than or equal to two-thirds of validators to be operating to create blocks. For example, a QBFT of:

* Four to five validators tolerates one unresponsive validator.
* Six to eight validators tolerates two unresponsive validators.

Networks with three or less validators can produce blocks but do not guarantee finality when operating in adversarial environments.

### Speed

For QBFT , the time to add new blocks increases as the number of validators increases.


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