Blockchains require nodes to operate. A node is a piece of software that connects to other nodes in the blockchain to create a network. Nodes are where data is stored, received and transmitted. They are crucial to network security and integrity.

All blockchain transactions must pass through nodes as they validate the transactions via a ‘consensus mechanism’, aka algorithm (mathematical calculations).

Each blockchain has a different protocol or way of validating transactions eg the Bitcoin protocol is different to that of Ethereum and has a different means of ‘consensus’. Thus what a node actually does in any given blockchain protocol will vary, however one thing remains; a node requires a piece of hardware to run on (just like any other piece of software or program).