A node is a computer or device that connects to the blockchain and uses a peer-to-peer (P2P) protocol. All nodes on a blockchain are connected to each other and constantly share the latest blockchain data with each other so they stay up to date. P2P protocols allow nodes to communicate with each other within a network.
A node communicates with all peers connected to it and monitors them. When a new block or transaction is received, it’s reported to the network by a peer. A node then verifies the accuracy of the reported data. To eliminate the possibility of double spending, the node tests each of a transaction’s terms. If the node receives an invalid transaction, it stops the data exchange with the peer.
In a P2P network, a peer who has attempted fraud is isolated, and all crypto nodes stop interacting with it.
Nodes can be online or offline. Online nodes receive, save, and broadcast all the latest blocks of transactions between other nodes, while offline nodes do not.