What is a Node/Validator
A validator (also known as a node) is someone who is in charge of transaction verifications on a chain. Once a transaction is verified, the validator will add the transaction to the distributed ledger.
In general, a validator will receive token rewards as an incentive for the "verification job". On the other hand, a validator who has misconducted behavior will receive a penalty (normally a temporary or permanent ban from the system).
The number of validators differs between blockchains. In addition, the type of validators varies based on different consensus mechanisms. Here, we only introduce the two most common types of validators.
Validators in the PoW System
In the PoW system, such as Bitcoin, validators are called miners. They obtain transaction verification rights by solving complex computational problems. The rewards they received were based on their "workload".
Validators in the PoS System
In the PoS system, such as Solana, Ethereum 2.0, Avalanche, etc, participants need to stake a specific amount of the network’s native token to become validators. Validators who correctly participate in the verification process will receive rewards. Detailed reward rules differ based on networks.
Node vs. Validator
There are three types of nodes:
- light node
- full node
- archive node
Light nodes, as their name implies, only download block headers rather than entire blocks. This reduced requirement enables users to join and interact with blockchain networks without the need for powerful hardware or high bandwidth. However, light nodes do not participate in the consensus process, meaning they cannot function as miners or validators.
Full nodes, on the other hand, actively participate in block validation and verify all blocks and states. While it is theoretically possible for full nodes to store the entire blockchain data, they usually cache only the most recent states for faster access. For instance, Ethereum full nodes retain the last 128 blocks.
Archive nodes possess the same capabilities as full nodes but also maintain an archive of historical states. This feature allows direct queries of past states without needing to derive them from current data. Although archive nodes can participate in block validation, they are not obligated to do so.
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(Thanks to skrbug for identifying an inaccuracy in this section.)
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