What is a Node?

Most people using "decentralized" crypto never actually connect to decentralized networks. They click buttons in MetaMask, transactions appear on Etherscan, and they assume distributed magic happened. In reality, their wallet hit Infura's servers—one company processing millions of requests. The actual decentralized part, thousands of independent computers validating transactions, sits beneath, invisible.

Those invisible computers are nodes. They're what makes blockchain work. When people say Bitcoin or Ethereum can't be shut down or censored—they're talking about nodes. Thousands of independent computers worldwide each maintain their own blockchain copy, each independently verify every transaction, and no single one is in charge. Kill one, the network keeps running. Shut down a hundred, still fine. You'd need to attack the majority of thousands simultaneously to corrupt the network—which is why it hasn't happened.

A node is a computer running blockchain software that maintains a copy of the ledger, validates transactions and blocks, and communicates with other nodes to keep the network synchronized. Not fancy, not magical—lots of computers redundantly doing verification work and cross-checking each other. "Decentralization" means there's no central server. Thousands of nodes worldwide each run the same software. When someone broadcasts a transaction, nodes propagate it across the network. When a miner or validator produces a block, nodes verify it independently. This redundancy makes blockchains censorship-resistant.

How Nodes Actually Work

Running a node means running software with several jobs. First, it maintains a local blockchain copy—storing every transaction and block. Bitcoin: about 550GB. Ethereum: over 1TB and growing.

Second, your node validates everything. New transactions? Check signatures, balances, rules, prevent double-spends. New blocks? Verify transactions, structure, proof, and chain building. Only after passing checks does it add the block.

Third, your node participates in peer-to-peer network. It connects to dozens or hundreds of other nodes and exchanges information. When you broadcast a transaction, it sends to peers, who forward to their peers, until the network sees it. Gossip protocol spreads information without central coordination.

Fourth, your node provides interfaces for applications. Wallets and dApps query nodes to check balances, read state, estimate fees, and broadcast transactions. Nodes expose APIs like JSON-RPC. This is how MetaMask and Uniswap interact with blockchains.

Synchronization is continuous. As blocks are created, nodes receive them, validate them, add them to chains, and update state—balances, smart contract storage, etc.

Types of Nodes

Full nodes are the gold standard—they download and validate the entire blockchain from genesis. They independently verify every transaction and block ever. This requires significant storage (hundreds of GB to TB), bandwidth, and processing power. Full nodes provide maximum security—they verify everything themselves. "Don't trust, verify." You have an independent view of blockchain state no one can manipulate.

Light nodes are less demanding. They download block headers but not full contents. They verify transactions exist in blocks using Merkle proofs but don't validate all transactions. Light nodes trust full nodes validated correctly but still verify cryptographic proofs. Suitable for mobile wallets and resource-constrained devices. Security trade-off is real but acceptable for many uses.

Archival nodes are full nodes keeping entire history including old state. Normal full nodes "prune" old data, keeping only recent state. Archival nodes keep everything forever, enabling historical queries. They require multiple TB storage and are typically run by block explorers and data analytics companies.

Validator nodes in proof of stake are full nodes that additionally participate in consensus by proposing and attesting to blocks. They stake cryptocurrency and perform specific consensus duties. Validator nodes are special category of full node with additional responsibilities.

Mining nodes in proof of work are full nodes that additionally attempt to mine new blocks by solving computational puzzles. They need specialized hardware—ASICs for Bitcoin, GPUs for some chains—and consume massive electricity. Full nodes plus mining functionality.

RPC nodes are full or archival nodes configured to serve requests from external applications. Companies like Infura, Alchemy, and QuickNode run fleets of RPC nodes as a service. Your MetaMask wallet probably connects to one of these rather than running its own node.

Why Running a Node Matters

Decentralization: Every additional independent node makes networks more resilient and harder to attack. If only a handful ran nodes, they could collude to change rules or censor transactions. With thousands of distributed nodes, attacks become impractical.

Security: Running your own node means you independently verify blockchain state. You're not trusting Infura's API or block explorers—you're checking cryptographic proof yourself. This matters for large value operations.

Privacy: Connecting to someone else's node reveals your IP address and which addresses you're querying. Running your own node means blockchain interactions don't leak metadata. Combined with Tor or VPN, this provides strong privacy.

Network participation: Blockchain networks rely on altruistic node operators providing bandwidth and resources. More nodes means better topology, faster propagation, and improved redundancy.

Reliability: If you're building dApps or running blockchain businesses, depending on third-party providers introduces failure points and rate limits. Your own infrastructure gives control, guaranteed uptime, and no API limits.

Requirements and Costs

Bitcoin full node: About 550GB storage (growing 60GB/year), moderate bandwidth (initially downloading hundreds of GB, then ongoing 200GB/month), minimal processing power. Any modern computer works. Can run on Raspberry Pi with external SSD. Bitcoin Core is free.

Ethereum full node: 1TB+ storage (2TB+ for archival), significant RAM (16GB minimum, 32GB+ recommended), faster CPU for validating smart contracts, substantial bandwidth (initial sync multiple TB, ongoing 500GB+/month). Requirements grow faster than Bitcoin.

Different Ethereum clients have different profiles. Geth is resource-heavy but feature-complete. Erigon is optimized for storage. Nethermind focuses on performance. Besu is Java-based and enterprise-focused.

Hardware costs for home nodes are modest—used desktop or mini PC with upgraded storage for $500-1000 initial investment. Electricity costs a few dollars monthly. Internet bandwidth is the bigger constraint—need uncapped or high-cap plans.

Cloud hosting alternative: VPS with sufficient specs costs $50-200/month. This trades ongoing costs for avoiding home hardware and bandwidth use. But you're trusting cloud providers and losing some censorship resistance.

Node Centralization Concerns

Node operation has centralizing forces. Running nodes requires technical knowledge most lack. Hardware and bandwidth requirements exclude users on low-end devices or poor connections. Cloud hosting concentrates nodes on AWS, Google Cloud, Azure. These push users toward third-party node services.

Infura and Alchemy each serve millions of requests daily. If they went down or censored transactions, large portions of Ethereum users would be affected. This centralization is pragmatic—most won't run their own infrastructure—but it contradicts blockchain's trustless promises.

Geographic concentration is another issue. Most nodes run in North America and Europe. Developing countries have fewer nodes due to infrastructure costs. This creates vulnerabilities—governments in major regions could pressure node operators or block traffic.

ISP-level censorship is a theoretical concern. If ISPs blocked blockchain P2P traffic, home nodes would struggle. This hasn't happened at scale yet. Running nodes over Tor or VPNs provides defense but with performance costs.

Cost and complexity trends are worrying. As blockchains grow, node requirements increase, potentially pricing out home operators. Ethereum's state growth is recognized problem—data required grows faster than Moore's Law. Solutions like statelessness are being researched, but it's a race between bloat and solutions.

The Future of Nodes

Light client protocols are improving dramatically. Ethereum's sync committee allows light clients to follow chains with minimal trust. As these improve, the gap between light clients and full nodes narrows.

Stateless clients are the long-term vision where nodes validate blocks without storing full state. Using Verkle trees and state proofs, validators could receive everything needed within the block itself. This would drastically reduce requirements, enabling more decentralization.

Peer-to-peer networking is evolving. libp2p provides modern networking that many blockchains use, improving connection management and transport flexibility. Better networking helps nodes operate reliably with less configuration.

Incentive mechanisms for running non-validator nodes are being explored. Currently, there's no direct economic reward for running full nodes that aren't mining or validating. This altruistic model works but limits scale. Some proposals suggest incentivizing full nodes through protocol rewards, though implementation is complex.

The Bottom Line

A node is a computer running blockchain software that maintains a copy of the ledger, validates transactions and blocks, and participates in peer-to-peer networks. Nodes are fundamental infrastructure—individual computers collectively forming decentralized networks. Running a node provides maximum security and privacy by verifying everything yourself rather than trusting third parties.

Full nodes provide the gold standard of security but require significant resources—hundreds of GB storage, decent bandwidth, and technical knowledge. Light nodes trade some security for lower requirements, suitable for mobile environments.

Running nodes matters for decentralization and security, but expecting all users to run nodes is impractical. Healthy blockchains have thousands of diverse, independent nodes, with most users connecting through light clients or node services. The balance between decentralization idealism and pragmatic usability is ongoing.

For users and developers serious about blockchain, understanding nodes is essential. For those who just want to use crypto, connecting to reputable node services is reasonable. The important thing is that the option to run your own node exists—that's what keeps networks honest.

References

1. Nakamoto, S. (2008). "Bitcoin: A Peer-to-Peer Electronic Cash System." https://bitcoin.org/bitcoin.pdf
2. Bitcoin Core. (2024). "Running a Full Node." https://bitcoin.org/en/full-node
3. Ethereum Foundation. (2024). "Nodes and Clients." https://ethereum.org/en/developers/docs/nodes-and-clients/
4. Gervais, A., et al. (2016). "On the Security and Performance of Proof of Work Blockchains." ACM CCS.
5. Decker, C., & Wattenhofer, R. (2013). "Information Propagation in the Bitcoin Network." IEEE P2P.
6. Ethereum Foundation. (2024). "Run a Node." https://ethereum.org/en/run-a-node/
7. Miller, A., et al. (2015). "The Bitcoin P2P Network." Financial Cryptography.
8. Biryukov, A., et al. (2014). "Deanonymisation of Clients in Bitcoin P2P Network." ACM CCS.
9. DAppNode. (2024). "Decentralized Node Infrastructure." https://dappnode.io/
10. Ethereum Foundation. (2024). "Ethereum Node Architecture." https://ethereum.org/en/developers/docs/nodes-and-clients/node-architecture/