What it means
A shared record of who owns what, kept by many computers at once, that no single company can change on its own.
Each new batch of transactions is added as a block, linked to the one before by a cryptographic fingerprint called a hash. Change an old block and every link after it breaks, which everyone else would see.
How it works
The computers that keep the record, called nodes, agree on each new block by a set of rules called consensus. On most networks today that's proof of stake: validators lock up tokens and lose part of them if they cheat.
Public blockchains such as Bitcoin, Ethereum and Base are open: anyone can read the record, send a transaction or check one in a block explorer. Nobody needs permission to take part.
That openness has a cost. Every transaction is visible, with its amounts and addresses, though not names. And a confirmed transaction can't be reversed, so a payment to the wrong address stays there.
A blockchain can also run programs, called smart contracts, that hold and move tokens by fixed rules. Stablecoins, exchanges and lending markets are all built this way.
Stablecoins like USDC and EURC are balances on a blockchain. That's why you can hold them without a bank keeping the record for you. Defied works on Base, a network built on Ethereum with low fees and fast confirmations. See what a stablecoin is.
Related terms
| Term | What it means |
|---|---|
| Onchain | Recorded on a public blockchain, where anyone can check it, rather than in one company's private database. |
| Base | A public blockchain built by Coinbase that runs on top of Ethereum, with low fees and fast confirmations. |
| Transaction | One action recorded on a blockchain, such as a payment, an exchange or a deposit. |
| Smart contract | A program that lives on a blockchain and runs exactly as written, holding and moving tokens by its own rules. |
This glossary explains terms in general. It isn't investment, tax or legal advice.