Ledger in Block Chain

A ledger is a kind of database where confirmed transactions are recorded

Centralised Database

• Bob is purchasing a product from Alice's shop. He is making an online transaction. The Bank subtract $4.00 from Bob's bank account and add $4.00 to Alice's account . The Bank records these transaction in a centralised database also known as a ledger.
• Only the Bank (trusted third party) has access to this ledger.

Distributed Ledger

• Blockchain platforms don't use a centralised database instead each node has a copy of the ledger.

• Cryptocurrencies such as Bitcoin only stores balance information in the distributed ledger.
• Blockchain platforms such as Ethereum can store any kind of information, such as identity information, patient information, real estate information, etc., in the distributed ledger.

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Public ledger / Permissionless Ledger

• When there is no central managing access to the ledger, this ledger, this ledger is called a public ledger or a permissionless ledger.

Private Ledger / Permissioned Ledger

• When there is a central authority managing access to the ledger , this ledger is called a private ledger or a permissioned ledger.

Additional Information

• Bitcoin and Ethereum nodes have copies of the ledger, but the ledger should be correctly depicted this way:

• In the next post i will explain why this ledger should look like this.