Block Chain - Blockchain Ledger

Definition: A blockchain ledger is a digital record book that stores all transactions made on a blockchain network. Instead of being stored in one place, it’s distributed across many computers (nodes).
Distributed:
Each participant in the blockchain has a copy of the ledger. This means no single person or company controls it, and everyone sees the same history of transactions.
Immutable:
Once a transaction is added, it cannot be changed or deleted. If someone tries to tamper with it, the rest of the network will reject the change. This ensures trust and transparency.
How it works:
- Transactions are grouped into blocks.
- Each block is linked to the previous one, forming a chain of blocks (hence “blockchain”).
- Every block has a unique cryptographic hash that makes tampering detectable.
Example:
- On the Bitcoin blockchain, the ledger records every single Bitcoin transaction since 2009.
- If Alice sends 1 BTC to Bob, this transaction is recorded permanently on the ledger, visible to everyone, but without exposing Alice’s or Bob’s personal identities.
Why it matters:
The blockchain ledger removes the need for a central authority (like a bank) to verify and store transactions. Instead, trust comes from mathematics, cryptography, and network consensus.