In the context of blockchain, a node refers to a device that runs the blockchains software to validate and store the complete history of transactions on the network. Nodes are an integral part of the blockchain infrastructure, responsible for maintaining consensus of a blockchains public ledger. They ensure that the blockchain is functioning properly and have the ability to reject transactions if they are malicious. Nodes communicate with each other, and the more nodes there are, the more decentralized the network is.

Nodes can be any electronic device with an IP address, such as a computer, router, modem, switch, hub, server, or printer. They can create, send, and receive blockchain data, and their primary purpose is to validate, record, and broadcast each transaction on the network. There are different types of nodes with differing use-cases, such as full nodes, light nodes, miner nodes, and validator nodes.

Full nodes store a full copy of the networks digital ledger and are responsible for providing a copy of the chain to new nodes. They are the backbone of a network and are responsible for executing each blockchains consensus mechanism. Light nodes, on the other hand, do not store a full copy of the blockchain and rely on full nodes to provide them with the necessary information. Miner nodes create and propose new blocks, while validator nodes confirm the legality of each subsequent batch of network transactions, known as blocks.

Anyone can set up a node for most cryptocurrencies by downloading the blockchains software onto their personal computer anywhere in the world. However, some blockchains, like Ripple, only allow certain nodes to participate.