In blockchain networks, a node can be thought of as any active electronic device connected to the network. It can be a computer, server, or even a smartphone that keeps a copy of the blockchain and participates in the consensus process. Nodes play a crucial role in ensuring network security and integrity, as they are responsible for validating transactions and blocks. Depending on their functionality, nodes can be categorized as full nodes, which store the entire blockchain, or light nodes, which store only a part of the blockchain and rely on full nodes for transaction verification.