An open ledger (like a blockchain) works as a shared digital record book:
A user creates a transaction.
The transaction is sent to many computers (nodes).
Nodes verify the transaction using consensus rules.
Verified transactions are bundled into a block.
The block is permanently added to the chain.
Every participant gets the updated copy of the ledger.
Key Features
Decentralized → no single owner
Transparent → everyone can verify records
Immutable → past records are hard to change
Secure → cryptography protects data
Blockchain Structure Visualization
┌─────────┐ ┌─────────┐ ┌─────────┐
│ Block 1 │──▶ │ Block 2 │──▶ │ Block 3 │
└─────────┘ └─────────┘ └─────────┘
▲ ▲ ▲
│ │ │
Previous Hash Previous Hash Previous Hash
Each block contains:
Transaction data
Timestamp
Cryptographic hash
Previous block hash
That linking creates the secure “chain.”