Node
A node is a computer that runs a blockchain network's software to share data and verify transactions with other participants.
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What Does a Node Do?
A node is a computer that connects to a blockchain network and runs the network software. This computer shares transaction and block information with other nodes. A specific type called a “full node” independently verifies the information it receives according to the network’s rules. This way, it doesn’t have to trust anyone else saying “this transaction is valid.”
In Bitcoin, a full node checks, for example, whether the same Bitcoin is being double-spent and if the amount of new Bitcoin in a block exceeds the allowed limit. The fact that a miner uses very powerful computers does not make an invalid block valid. The node rejects such a block.
Difference Between a Node and a Wallet (With an Example)
A wallet on your phone might connect to a server to display your balance. In this case, you use the wallet interface while the server queries the network records on your behalf. When you run your own full node and connect it to a compatible wallet, you can perform these queries using records you have verified yourself. The wallet manages spending keys; the node verifies network information. Although both can exist within the same application, their roles are different.
Does Running a Node Earn Money?
Not every node is a miner or a validator. Running an ordinary Bitcoin full node does not automatically earn BTC rewards. Mining requires an additional computational race to produce new blocks. In some other networks, becoming a validator requires staking tokens and running additional software.
Running a full node requires disk space, internet bandwidth, and maintenance. A “pruned” node can use less disk space by deleting a portion of old block data after verification. This feature does not mean the past was never verified. When comparing node types, one should distinguish between the amount of data stored and the verification performed.