What is a blockchain node?
In short, a node is a communication endpoint within a decentralized network, such as a blockchain network. Blockchains are decentralized, immutable, digital distributed ledgers shared across a peer-to-peer network of nodes, that allow for the secure and transparent recording of transactions.
Nodes play a crucial part in the functioning of blockchain technology, by participating in the validation of transactions, maintaining a copy of the blockchain, and providing advanced services to users. Decentralized networks such as Ethereum and Bitcoin store their blockchain data on several thousands of nodes across the world, instead of using a single central authority.
There are several types of nodes, such as full nodes, light nodes, masternodes, archival full nodes, authority nodes and staking nodes. Each type of node has a specific purpose and contributes to the stability and security of the network. Nodes can be run by individuals or service providers such as Amazon, and the number of nodes on a blockchain network can vary widely, with some networks having thousands and others having only a few hundred. Let's take a closer look at how blockchain nodes work.
What is the difference between a node and a miner?
To illustrate this, we'll use the PoW (Proof-of-work) consensus mechanism on the Bitcoin blockchain as an example. Bitcoin miners earn BTC by finding and publishing new blocks. This is both an incentive and a reward for keeping the network secure and ensuring that all transactions are valid. Anyone can download the entire Bitcoin blockchain and validate blocks, and Bitcoin nodes can be run by anyone in the world with the right hardware and internet connection.
In order to select valid transactions to form a new block, a miner needs to run a full node. A miner cannot determine the validity of proposed transactions without a full node, because the miner doesn't have access to full blockchain history (think the current blockchain's transaction history). A miner is always a full node, but the opposite is not always true, as a device can run a full node without actually creating new blocks of transactions itself, whereas a miner simultaneously tries to create a new blocks as well.
What are types of blockchain nodes?
Full nodes are the most important type of blockchain nodes. They are responsible for validating new blocks of transactions and maintaining a copy of the entire blockchain. They are an essential part of blockchain infrastructure, as they maintain the integrity of the network and ensure that all transactions are valid. Full nodes also play a key role in the Proof of Work or Proof of Stake consensus algorithms that are used by many blockchain networks, such as Bitcoin and Ethereum, and allow smart contracts to be run.
Pruned full nodes
Pruned full nodes have a set memory limit and prioritize security over storage. When installed, the node downloads a copy of the entire blockchain and beings deleting everything except the metadata from its oldest books. Retaining the metadata allows it to maintain sequence. The node only keeps the most recent entries on the blockchain, until capacity is reached.
Light nodes, or lightweight nodes, also also known as a Simplified Payment Verification (SPV) node, are another type of node. Unlike full nodes, which store a copy of the entire blockchain, lightweight nodes only store block headers and rely on other full nodes to provide them with the necessary information. This allows them to operate with a smaller storage footprint and less computational power, making them useful for users who have limited storage space or are looking for a more lightweight way to access the blockchain.
Archival full nodes
Archival full nodes, also known as super nodes, are full nodes that store the entire transaction history of a blockchain network. These nodes are useful for providing long-term data storage for the network, as well as for providing access to historical data for researchers and developers.
Authority nodes, also known as mining nodes or miner nodes, are nodes that are responsible for maintaining the network by creating new blocks and broadcast the transactions to the network. These nodes are typically rewarded for their work with new cryptocurrency.
Lightning nodes are specifically designed to facilitate fast and low-cost transactions on the Bitcoin blockchain network. They are built on top of the traditional full nodes and use the lightning network, a layer 2 scaling solution, to enable off-chain transactions. These off-chain transactions are settled on the blockchain only when necessary, which allows for a significant increase in the number of transactions that can be processed per second. Lightning nodes offer features such as instant payment and atomic multi-path payments (AMP). Running a lightning node requires some technical knowledge, but it can be a great way to help scale the Bitcoin network.
Masternodes are another type of node that is becoming increasingly popular. These nodes are responsible for providing advanced services to the blockchain network, such as instant transactions and privacy features. They typically require a significant amount of collateral, such as a large number of coins, in order to operate. Masternodes, in addition to validating, preserving, and broadcasting transactions, may also assist other events on the blockchain, depending on their nature, such as managing voting events, but they cannot add new blocks to the blockchain.
Staking nodes participate in the consensus algorithm of Proof of Stake blockchains such as Ethereum 2.0 (Ethereum used PoW before the Ethereum Merge). A staking node can be one user or a staking pool (several users who pool their crypto funds). To set up a staking node, users have to lock a certain amount cryptocurrency of that ecosystem (so, ETH for Ethereum) and are rewarded for validating new transactions.