What is a Node?

In the context of the Bitcoin blockchain, a Node is a program supporting the key functions of Bitcoin – validating transactions and blocks that store transactions. Validated blocks are added to  blockchain, which continues to grow. So running a Node helps support and grow Bitcoin.

Nodes act either as a communication endpoint or as a redistribution point that may perform different functions. 

Any device that connects to the cryptocurrency’s interface may be called a node in the sense that they communicate with each other through the blockchain network.

Nodes can also transmit information about blocks and transactions within the blockchain network of devices by using Bitcoin’s p2p2 protocol.

Each node has its predefined functions, therefore different types of Bitcoin nodes exist. 

Full Node

A full node is responsible for verifying, authenticating, and storing all transactions occurring on a blockchain network and acts as a core server, which means it is data-heavy. Given the data load a full node can be expensive to run and requires advanced computing power and energy. As per Datalight’s research, over 10,000 full nodes are operating on the Bitcoin network. 

In addition to the overall security and validity of a Bitcoin network, a full node has other specific responsibilities that make it different from other nodes. Two important distinguishing features are:

• A full node is responsible for inspecting the authenticity of each digital signature before adding a new block to the blockchain. 

• A full node has the authority to reject transactions or blocks that don’t follow the protocol. 

10,500

The number of reachable Nodes on the Bitcoin Network, as of March 2021. source: www.bitnodes.io

Lightweight Node

Unlike full nodes, Lightweight nodes do not contribute to the security of the Bitcoin network as they don’t record transactions.

Also known as Simplified Payment Verification clients, these nodes enable users to check if transactions were included in a block or not, without requiring a user to download the whole copy of the blockchain. Essentially, lightweight nodes participate in the network as communication endpoints. 

Miners are Not Nodes

While a full node verifies all the transactions and has a complete copy of the blockchain, a miner creates the blocks which the nodes keep. A miner works on a transaction for about 10 minutes to solve a cryptographic puzzle and comes up with the best combination to store that data.

On the other hand, nodes record that result forever after verifying the data. So, miners are completely different from nodes but the interchangeable language of Bitcoin as meant that sometimes the two things are conflated..