What is Blockchain?
A blockchain is a shared database maintained by many independent computers, where records are grouped into blocks cryptographically linked in sequence. Once data is recorded, changing it without everyone noticing is practically impossible.
Also known as: distributed ledger · block chain · DLT
In plain terms
Think of a ledger that thousands of computers keep identical copies of at the same time. When new transactions arrive, they are grouped into a block, the network agrees the block is valid, and it is added to the chain for everyone to see.
Because every block is mathematically connected to the one before it, editing an old record would break those links, which makes the history tamper-evident rather than merely private.
How it works
A user signs a transaction with their private key and broadcasts it to the network. Transactions wait in a queue until a block is produced.
A validator or miner bundles transactions into a block and the network reaches consensus on it, either through proof of work, proof of stake or another mechanism defined by that chain's rules.
Each block stores a cryptographic hash of the previous block, chaining them in order. Validators then all update their copies, so the ledger stays synchronized without a central operator.
Example
Hypothetical: a buyer pays a supplier by transferring a stablecoin. The transfer is signed with the buyer's wallet, becomes part of the next confirmed block, and within seconds both parties can independently verify the payment in the public history.
Why it matters for founders and investors
Blockchains let strangers exchange value and record ownership without a trusted intermediary, which is the foundation for tokens, smart contracts and tokenized assets.
For founders and investors, the relevant questions are practical ones: which chain an asset lives on, who validates it, how fast and how cheap transfers are, and what happens if the chain or its validators fail.
Common misconceptions
A blockchain is not automatically better than a normal database. It is designed for shared records among parties who do not fully trust each other; for data a single company controls, a conventional database is cheaper and faster.
Immutability means records are hard to change, not that they are correct. If bad data is written on-chain, it stays there unless the system has a correction mechanism.
Frequently asked questions
Is a blockchain the same as a distributed ledger?
A distributed ledger is the broader category: any database replicated across sites. A blockchain is a specific type that groups records into hash-linked blocks. The terms are often used interchangeably.
Who controls a blockchain?
It depends on the design. Public blockchains like Bitcoin or Ethereum are operated by thousands of independent validators and governed by their protocol rules and community processes. Private or permissioned blockchains are controlled by a defined group of organizations.
Can data on a blockchain be deleted?
Ordinarily no. Records are designed to be permanent. Some chains support limited deletion or pruning of certain data for privacy reasons, but economic records such as transfers are effectively permanent.