Node

Running a node means running the blockchain's client software so a machine can independently enforce the protocol's rules rather than trust someone else's word for it. A node checks digital signatures, rejects double-spends, refuses blocks that break consensus, and shares valid data with its peers. This is what turns a blockchain from a database controlled by one operator into a shared ledger that thousands of independent participants agree on.

Not every node does the same job. A full node keeps a verified copy of the chain and checks every transaction against the rules itself, making it a trust anchor for the network. An archive node goes further, retaining the entire historical state so past balances and contract data can be queried at any block. A light node, common in mobile wallets, downloads only block headers and asks full nodes for proofs, trading some independence for speed and low storage.

Node count and geographic spread matter because they determine how resistant a network is to censorship or a single point of failure: Bitcoin, for example, has tens of thousands of publicly reachable nodes spread across well over a hundred countries, many run on ordinary home hardware. Running a full node costs bandwidth and disk space, which is one reason lighter alternatives exist, but it is the one action that lets a user verify their own holdings and transactions without relying on an exchange or wallet provider.

Nodes are distinct from miners or validators: a node can simply relay and check data, while mining and staking additionally compete to produce new blocks.