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What is a node?
A node is a computer running a blockchain's software and connected to its network. A full node downloads and checks every block against the rules itself; a light node keeps only block summaries and asks full nodes for details.
What it means for you
Your wallet relies on some node to show your balance and broadcast your transactions. If that node belongs to a company, it can see your addresses and balances; running your own node lets you verify the chain yourself and keeps that information private.
How it works
A full node downloads each block and checks every transaction against the consensus rules itself, rejecting anything invalid whoever proposed it. On Ethereum a node runs two programs: an execution client that runs transactions in the EVM and holds the current state, and a consensus client that follows proof of stake. Full nodes prune old state; archive nodes keep every historical state. Light nodes download only block headers; on Bitcoin, the similar SPV method checks that a transaction is in a block without downloading the whole block. A validator is a node that also runs validator software with 32 ETH at stake; an ordinary node verifies without staking.
Sources: ethereum.org: Nodes and clients, Bitcoin developer glossary, ethereum.org: Proof-of-stake · checked 4 October 2026
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