A Bitcoin node is a computer that connects to the Bitcoin network. It is part of the network infrastructure that helps to keep the Bitcoin network running and secure.
Nodes are an important part of the Bitcoin network because they relay transactions and help to keep the blockchain secure. They do this by validating transactions and blocks, and then propagate them across the network.
Nodes also help to keep the Bitcoin network decentralised by ensuring that there is no single point of failure.
Without nodes, the Bitcoin network would not be able to function. They are an essential part of the infrastructure that keeps the Bitcoin network running smoothly.