What is full node?

A node that downloads every block and independently checks every rule, keeping the current state without trusting anyone else's summary of it.

Running one is what lets you verify your own balance rather than believe a server, and it is the reason a network's rules cannot be changed by a handful of large operators alone: a node that disagrees simply rejects the blocks. Storage and bandwidth are the cost, and modern clients prune old block data while still validating everything on the way through.

Most wallets are not full nodes; they ask someone else's. Wallets that let you point at your own node give you the verification benefit without running the wallet software on the same machine as the chain data.

The misconception worth correcting is that running a node earns money. It does not. Mining and validating earn rewards; verifying does not. What a node buys you is the ability to check rather than trust, which is a different kind of return.

How it works

A full node starts from the genesis block and validates every block since, checking signatures, rule compliance, and that no coin is spent twice. Having done that, it knows the current state from first principles rather than from anyone's report.

Three things follow from that:

• You verify your own balance. A light wallet asks a server what you own and believes the answer. A full node computes it.
• You enforce the rules you chose. If a miner or validator produces a block breaking the rules your software implements, your node rejects it regardless of how much hash power or stake stands behind it.
• You leak nothing. Querying someone else's node tells them which addresses interest you, which is a real privacy cost most people never account for.

Resource requirements differ by chain and grow over time. Bitcoin's full chain history runs to hundreds of gigabytes, and Bitcoin Core supports a pruned mode that discards old block data after validating it, with a documented minimum prune target of 550 megabytes of block storage (source: Bitcoin Core documentation). Pruning does not weaken validation, because every block was checked on the way through; it only removes the ability to serve history to others.

An archive node is the opposite extreme, keeping every historical state for query purposes, and it is dramatically larger.

Example

Illustrative setup. You run a pruned Bitcoin node on a small computer at home and point your hardware wallet's companion software at it. Your balance is now computed by software you control from blocks you validated yourself. Nobody learns which addresses you hold, and a change to the rules that your node does not accept cannot silently affect what you see.

Why it matters when you buy

Coins on an exchange are a database entry you cannot verify at all, and coins in a light wallet are verified by someone else. If a purchase is large enough that you plan to hold it in self custody long term, running your own node is the step that removes the last party you have to trust. Compare where to buy at the exchange pages.

Related terms

node — the general term, light client — the trusting alternative, archive node — the full-history variant, self custody — what a node completes, block explorer — the third-party version of the same lookup, consensus — the rules a node enforces.

Questions

Do I earn anything for running a full node?

No. Rewards go to miners and validators. A full node's return is verification and privacy rather than income.

How much disk space do I need?

It depends on the chain and whether you prune. Bitcoin Core's documented minimum prune target is 550 megabytes of block storage, while keeping the full history requires hundreds of gigabytes. Check the specific client's own documentation.

Can I use a full node with a hardware wallet?

Yes, and it is a common combination. The node validates and reports; the hardware wallet holds the keys and signs. Neither needs to trust a third-party server.