The Nodes in the Bitcoin Network
Nodes are all computers connected to the Bitcoin peer-to-peer system. They are computers that communicate with each other on the network. Nodes verify transactions and propagate newly-timed blocks in the network. They can also have additional functions.
Various Types of Nodes
Some nodes are called “full nodes”. They have access to the complete blockchain. Each full node can independently verify transactions. Other nodes, the so-called “lightweight nodes”, can only see the last blocks of the blockchain. Thus, they do not have access to the complete blockchain. Lightweight nodes also verify open transactions, but, unlike full nodes, they only use a simplified method.
The Difference to Miners
The blockchain is not continued by the nodes, but only by the miners. Miners themselves are part of some nodes. A node with mining function creates blocks from the transactions that were previously validated by other nodes. Miners, therefore, only bring transactions into a row and document them in a block. Nodes assess the validity of the transactions.
In general, nodes do not trust but control each other. Nodes that post invalid transactions on the network are isolated by honest nodes. The more invalid transactions are published by nodes, the longer these nodes will be blocked or even completely excluded from the network.
Antonopoulos, A. M. (2017). Bitcoin Q&A: What is the role of nodes? Retrieved January 25, 2019, from https://www.youtube.com/watch?v=fNk7nYxTOyQ
Antonopoulos, A. M. (2017). Mastering Bitcoin: Programming the Open Blockchain (2nd ed.). Sebastopol: O’Reilly Media.
Narayanan, A., Bonneau, J., Felten, E., Miller, A., & Goldfeder, S. (2016). Bitcoin and Cryptocurrency Technologies: A Comprehensive Introduction. Princeton, New Jersey: Princeton University Press.