A node in a cryptocurrency network is a computer that is responsible for validating transactions and storing blockchain data, which is fundamentally different from miners and stakers who rely on nodes to access the ledger. Nodes include light nodes (for verifying partial data), full nodes (for storing the entire blockchain), and master nodes (for executing governance and supporting additional functions such as private transactions). Master nodes, originally pioneered by Dash, typically require substantial collateral and resources, while light nodes and full nodes are more accessible and support network decentralization.