Node
Nodes are foundational infrastructure for blockchains and provide two critical functions for their operations.
- Storing and preserving the ledgers transaction history.
- Confirming the present state of the network via communication with each other.
Implying blockchains “live” on their nodes.
Typically Nodes are maintained using PCs but cryptoassets with extensive transaction history may require a server to operate.
And,
Nodes are not limited to computer hardware. In theory any device, such as a cellphone, with an Internet connection can serve as a node. If the blockchains history is lightweight enough it can fit onto the connected devices memory.
All miners are nodes but all nodes are not miners. Miners distinguish themselves from regular nodes by verifying the transaction activity of the blockchain.
Full nodes store and update a copy of a blockchain’s entire history. In some cases blockchain’s allow nodes that aren’t full nodes. Giving nodes the option to start updating based on the recent state of the network without copying its full history.
Nodes do not need to operate continuously. But do need to update to the present state of the network when they reconnect to the Internet.
In theory a blockchain can operate with only one node. In practice this would not be a stable way to operate a network and the more nodes supporting a blockchain the more secure it is.