This distributed ledger is the core persistent layer in the blockchain architecture. It provides a decentralized and distributed database containing the transaction entries. These entries are recorded in the order of its occurrence and composed into hashed blocks. The database or the ledger, therefore, represents a chain of hashed blocks of transactions with each block referring to the previous block in the chain. The ledger is shared across the blockchain network, which means every node has a copy of the ledger, and each node verifies the transactions independently. When every node agrees and confirms the authenticity of the transaction, the ledger is said to be in consensus. The blockchain network uses different consensus algorithms to arrive at the consensus. The consensus algorithm is a set of rules and conditions that governs the transaction. The blockchain network implemented for the public has a permissionless ledger, while in a private network or a consortium, a ledger can be made permissioned. A permissioned ledger introduces some form of access control in the way transactions are accessed and managed.