Blockchain is a type of shared digital ledger that records transactions in a way that is very hard to alter once they are saved. It stores data in “blocks” that are linked together in chronological order, forming a secure “chain” of records.
Core idea
Blockchain is a database that is distributed across many computers (nodes) instead of being kept in one central server.
Every participant can hold a copy of the ledger, which makes the system more transparent and resilient to single points of failure.
How it works
Transactions (like sending cryptocurrency or updating ownership of an asset) are grouped into blocks, each block containing the data, a timestamp, and a cryptographic hash of the previous block.
Because each block references the previous one via its hash, changing old data would require changing all later blocks and convincing most of the network, which makes tampering extremely difficult.
Key properties
Decentralized: No single authority controls the ledger; updates are validated by a network consensus mechanism (for example, proof of work or proof of stake).
Immutable and transparent: Once recorded and confirmed, data is effectively permanent and visible to network participants, providing a verifiable history of transactions.
What it is used for
Cryptocurrencies like Bitcoin and Ethereum use blockchains to track balances and prevent double spending without a central bank.
Beyond crypto, blockchains are used or piloted for supply-chain tracking, digital identity, financial settlements, and other applications where secure, auditable records are important.
Why it matters
Blockchain can reduce reliance on intermediaries (such as banks or clearinghouses) by letting parties transact directly while still trusting the shared record.
This can lower costs, increase efficiency, and improve traceability in systems that need a trustworthy record of who did what and when.
–
