Node
In simple terms
A node is a computer that stores a copy of all cryptocurrency transactions and helps make sure everything is honest. Think of it like a security guard at a store who keeps a record of every sale to prevent cheating.
Definition
A computer that maintains a copy of the blockchain and helps validate transactions.
In depth
A node is a networked computer that maintains a complete or partial copy of the blockchain ledger and participates in transaction validation and consensus mechanisms. Nodes receive pending transactions, verify them against the current state and protocol rules, and propagate valid transactions to other nodes. Full nodes store the entire transaction history and can independently validate new blocks, while light nodes store only essential data and rely on full nodes for verification. The distributed nature of nodes across the network eliminates single points of failure and enables decentralized consensus without requiring trust in a central authority.
How does Node work?
A node is a computer running blockchain software that keeps its own copy of the ledger. On first start it connects to peers, downloads the chain from the beginning, and independently verifies every block against the network's rules, checking signatures, that coins were not already spent, and that blocks are correctly formed. Anything failing those checks is rejected regardless of who sent it. Once synced, the node relays new transactions and blocks to peers and stays current. A full node stores enough to validate everything, an archive node retains all historical state, and a light client checks headers while trusting others for the rest.
An example
Someone runs a Bitcoin full node on a small home computer with a one-terabyte drive. The initial download takes days and verifies the chain's entire history. Afterwards it uses modest bandwidth relaying new blocks arriving roughly every ten minutes. The node earns nothing, which is not its purpose. What it provides is the ability to check the operator's own transactions against rules the operator enforces, rather than trusting another party's answer.
Figures are illustrative only.
What beginners get wrong
- Assuming a node produces income, when validating blocks pays nothing by itself and is a separate activity from mining or staking.
- Believing a wallet app is a node, when most wallets query someone else's server and display whatever balance that server reports.
- Underestimating storage needs and initial sync time, then abandoning a partly downloaded chain that was never actually validating anything.
- Exposing a node's RPC interface to the open internet without authentication can let strangers issue commands to it, including wallet commands.
Related terms
Part of
What is cryptocurrency, and how does it work? — the subject page for cryptocurrency basics, with all 23 of its definitions in one place.
Educational only — not financial advice.