TL;DR: Running a node means operating a computer that participates in a blockchain network by downloading, validating, and relaying transactions and blocks. It gives you direct, trustless access to blockchain data without relying on any third party. While running your own node offers maximum sovereignty and privacy, it comes with real costs in hardware, maintenance, and operational complexity that most developers and teams choose to offload to infrastructure providers.
The Simple Explanation
At its core, running a node means installing blockchain client software on a machine, connecting it to the peer-to-peer network, and letting it sync the full history of the chain. Once synced, your node independently verifies every new block and transaction according to the network's consensus rules. It does not trust other nodes. It checks everything for itself.
This is the fundamental promise of blockchain: "Don't trust, verify." When you run your own node, you are not taking anyone's word for the state of the chain. Your machine downloads the raw data, executes the transactions, and arrives at the same state as every other honest node in the network. If someone tries to feed your node an invalid block or a fraudulent transaction, your software rejects it automatically.
Running a node also means your application has a direct, private connection to the blockchain. When you query a wallet balance or submit a transaction through your own node, that request does not pass through any third-party server. No one can log your queries, throttle your access, or censor your transactions. You are a first-class participant in the network.
What Running a Node Actually Involves
The reality of running a node goes well beyond installing software. On Ethereum, a full node requires two separate client programs running simultaneously: an execution client (like Geth, Nethermind, or Erigon) and a consensus client (like Prysm, Lighthouse, or Teku). These two clients communicate with each other through an authenticated connection, and both must stay synced and healthy for the node to function properly.
