A node is a computer or device running blockchain software that connects to a cryptocurrency network. By communicating with other nodes, it helps store blockchain data, relay transactions and blocks, and enforce the network’s rules so everyone can agree on the same shared ledger.
What nodes do in a blockchain network
When you broadcast a transaction, it typically reaches the network through one or more nodes. Nodes pass that information along, check that it follows protocol rules, and update their local view of the chain as new blocks are added. This constant syncing and cross-checking is what lets a blockchain operate without a central server. In Bitcoin, for example, nodes validate that transactions are properly signed and that coins are not spent twice, then they propagate valid data to peers.
Types of nodes and practical examples
Not all nodes perform the same role. Full nodes store and independently verify the complete rule set of a blockchain, which is why they are often described as the backbone of decentralization. Light nodes, sometimes called SPV clients, rely on full nodes for some data while keeping a smaller footprint, which is common for mobile wallets.
On proof-of-stake networks, validator nodes propose and attest to blocks according to consensus rules, often requiring staked collateral. On proof-of-work networks, mining nodes focus on producing blocks, while full nodes verify them, meaning mining power and rule enforcement are not the same thing.
Why nodes matter
Nodes make blockchains resilient and trust-minimized by distributing verification and data across many independent operators. The more diverse and widely run the nodes are, the harder it is to censor transactions, rewrite history, or quietly change the rules, which strengthens the security and openness of the crypto ecosystem.