What are blockchain nodes and clients?

Nodes and clients are terms used to describe the participants and software involved in a public blockchain network.

Public blockchains are open-source digital ledgers, typically used to manage cryptocurrency transactions and other types of data.

In order to interact with cryptocurrency-based blockchains, participants typically need to first download a specific type of software onto their computer device. 

After downloading this software, people can use the blockchain to perform several different actions. 

From interacting with a crypto wallet and using a decentralized application (dApp), to voting on proposals with governance tokens, client software plays the important role of connecting users’ devices to the crypto ecosystem.

The software used to interact with a blockchain is known broadly as client software. 

You can think of client software as the link between an individual’s computer and the blockchain itself as well as the other blockchain users that are connected to the network. 

Everyone running client software in order to interact with the blockchain network is known as a node. Each public blockchain is collectively managed by a decentralized network of nodes. 

If you want to learn more about how these nodes operate with each other in order to reliably store information in a decentralized way, check out the Kraken Learn Center article What is a blockchain consensus mechanism?

You might want to check out our article What is blockchain technology? first.

Getting familiar with how blockchains work and what you can use them for might be helpful context for you to understand first – before you learn more about nodes and clients.

Nodes are the backbone of decentralized blockchain networks and use their computers to perform a variety of essential functions.

Some of the most common types of nodes and their roles are:

• Full node: Verify all new blocks of data and maintain a complete record of all historical transactions.
• Light node: Store a partial copy of the blockchain, oftentimes the most recent history of transactions.
• Archive node: Maintain a complete record of all transactions and historical states (for smart contract-based blockchains).
• Miner node: Participates in the proof-of-work mining competition to help secure the network, verify transaction data and win the right to propose new blocks.
• Staking node: Participates in the proof-of-stake process to help propose and validate new data in exchange for rewards.
• Lightning nodes: Connect the Bitcoin blockchain to the Lightning Network, keep record of all payment channel activity and help to identify the most efficient routes for payments between a sender and receiver.

All nodes contribute toward the security of the blockchain network they participate in, acting as independent fail-safes against any localized attack.

In this way, the larger and more distributed the network of nodes, the more secure and resistant to attack the blockchain ledger should be.

Mining and staking nodes, in particular, play an important role in protecting their respective networks against majority attacks. If a malicious agent wanted to corrupt a blockchain and do something like manipulate the order of inbound transactions or block pending payments, they would need to gain control over at least 51% of the network. 

For a blockchain network comprising a low number of nodes, this may not be too difficult to achieve. However, a large network with thousands of nodes would be much harder to attack.

Hashrate is a key metric used to gauge how much computational power is being directed toward winning the proof-of-work mining competition. The higher the hashrate, the greater the amount of resources a malicious agent would need to source to initiate and sustain their attack. 

If you want to learn more about the proof-of-work mining process and the role nodes play in it, check out the Kraken Learn Center article What is bitcoin mining?

For proof-of-stake blockchains, staking nodes must purchase and commit an amount of native tokens to participate in the validation process. Per this mechanism, a malicious agent would have to invest a sizable amount before they could execute an attack. Additionally, many PoS blockchains automatically confiscate staked coins via “slashing” if validators break protocol rules. 

If you want to learn more about the proof-of-stake staking process and the role nodes play in it, check out the Kraken Learn Center article What is crypto staking?

Blockchain clients are pieces of software that nodes run to connect to a blockchain network. 

From these clients, developers can create various applications such as block explorers and cryptocurrency wallets.

Most blockchains have their own natively developed clients. However, it’s not enough to provide nodes with only one software option for connecting to a blockchain.

If the codebase contains bugs or vulnerabilities, all nodes in the network would likely be affected and the network may suffer outages or attacks.

To combat this client diversity issue, many leading blockchains actively encourage third-party developers to create their own client software using whichever programming language they prefer. 

This gives node operators more options to consider when connecting to a blockchain.

Promoting the use of different programming languages also means each client codebase will be uniquely different from one another, helping to reduce the potential widespread impact of bugs or vulnerabilities.

To help illustrate this point, imagine a blockchain ledger as a city and each client as a different form of transport that connects commuters to the city center. 

If every commuter has to use the same form of transport to enter the city, it creates congestion issues. It also means that any maintenance work or strike action could prevent everyone from getting to work on time, since they all depend on the same system. 

However, if you have multiple ways of accessing the city, such as train connections, trams, ferries, buses, bicycle lanes, and more, there will likely be far less problems.

In summary, nodes and client software are the integral features that facilitate peer-to-peer, decentralized blockchain networks. 

Without these important pillars, it would not be possible to have secure, borderless cryptocurrencies that operate without the need for centralized intermediaries.

Now that you have learned about nodes and clients, as well as the exciting world of blockchain technology, are you ready to take the next step in your crypto journey?

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