Node (Cryptocurrency)

A node in cryptocurrency is any computer that runs the blockchain's software client and participates in the network by storing, validating, and relaying transaction data. Nodes form the backbone of decentralized networks — without them, no blockchain could function. They collectively maintain consensus about the state of the ledger, ensuring no single entity controls the truth about who owns what.

Different types of nodes serve different functions. Full nodes download and verify the entire blockchain history, independently checking every transaction against the protocol rules — they are the ultimate arbiters of validity. Light nodes (or SPV nodes) store only block headers and rely on full nodes for detailed transaction data, requiring less storage and bandwidth. Archive nodes store the complete historical state at every block, consuming terabytes of storage but enabling queries about past states. Mining nodes (in PoW) or validator nodes (in PoS) not only validate but actively propose new blocks.

Running a node is a fundamental act of decentralization. Bitcoin has approximately 15,000 reachable full nodes globally, while Ethereum has around 6,000. The more nodes a network has, the more resilient it becomes against censorship, attacks, and single points of failure. This is why node requirements matter — if running a full node requires expensive hardware (like Solana, which needs 128GB RAM), fewer individuals can participate, potentially centralizing the network among well-funded operators. Bitcoin's relatively modest requirements (500GB storage, modest CPU) have been a deliberate design choice to keep node operation accessible.