Node
In short A node is a computer running blockchain software that stores the ledger, checks transactions and blocks against the rules, and relays them to peers.
A node is any computer connected to a blockchain network that runs the client software. Together, nodes keep copies of the ledger, pass transactions and blocks to each other, and enforce the rules. No single node is in charge; the network stays consistent because every honest node applies the same rules to the same data.
There are several kinds. A full node downloads and verifies every block and rejects anything invalid. An archive node also keeps every historical state, which block explorers and analytics tools need. Light clients store only block headers and rely on full nodes for details. On proof-of-stake chains, validator nodes also propose and vote on blocks, while on Bitcoin, mining nodes build blocks and other full nodes check them.
For token holders, nodes matter even if you never run one. Your wallet, the DEX you trade on, and the price tracker you check all read data from some node, usually through an RPC provider. If that provider is slow, down, or malicious, you may see wrong balances, stuck transactions, or failed swaps, even when the chain itself is fine. The number of independent nodes also says a lot about how decentralized and censorship-resistant a network is.
If transactions keep failing or balances look wrong, try a different RPC endpoint before assuming funds are lost. Only add custom RPC networks from sources you trust, because a fake RPC can show false data. When evaluating a new chain, check how many nodes exist, whether anyone can run one, and what hardware it takes, since very high requirements can concentrate the network in a few data centers.