In cryptocurrency, a “node” refers to one of several computers connected to a network. Nodes help to maintain the blockchain by validating and relaying transactions on the network. They also store the history of all transactions carried out on the network up until the latest block.
Since blockchains use a decentralized network of nodes, no central authority governs the network or stores all of the data. Instead, each node in the network stores a copy of the blockchain data, and all nodes work together to validate and relay transactions. New transactions or blocks are broadcast from one node to another, ensuring each node has an up-to-date copy of the blockchain. When a node receives a new transaction or block, it will first verify its validity before adding it to its own copy of the blockchain.
Relevant software must be installed on a computer in order to run a node on a blockchain network. On the Bitcoin blockchain, for example, a node must constantly run the Bitcoin Core software, which enables computers to run, verify and store transactions on the blockchain in a timely manner.