HOW BLOCKCHAIN WORKS
Plain English
A blockchain is a shared ledger that thousands of computers keep copies of. When you send crypto, that transaction gets added to a 'block' that gets chained to all previous transactions. Once recorded, it can't be changed — ever.
Going deeper
A blockchain is a distributed ledger technology (DLT) that records transactions across many computers simultaneously. Each 'block' contains a batch of transactions, a timestamp, and a cryptographic hash of the previous block — forming an unbreakable chain. To add a block, participants (nodes) must reach consensus through mechanisms like Proof of Work (mining) or Proof of Stake (validators). Because the data is replicated across thousands of nodes worldwide, there is no single point of failure. Altering historical data would require re-computing every subsequent block faster than the honest network — computationally impossible.
Examples
The Unalterable Ledger
You send 1 BTC to Alice. This transaction is broadcast to thousands of nodes worldwide. Miners validate it and include it in a block. That block is linked to the previous one. Years later, this transaction is permanent — Alice can always prove she received it.
Consensus in Action
Imagine 10,000 computers all have a copy of the same spreadsheet. When a new transaction is added, 51%+ must agree it's valid before it's recorded. One hacker can't change the record because all the other copies contradict it.