Block, Blockchain and Distributed Ledger Technology
What is a ledger?
In layman’s term, ledger is a set of records that helps keep track of all business financial activities in an Organization. In other words, Ledger is a database where confirmed and validated transactions are recorded.
E.g. When Alex sends US $4 to Bob, it passes through central system like bank and bank records these transactions in centralized database called ledger of the bank.
What is Distributed Ledger Technology?
DLT is based on Peer to Peer (P2P) network concept. (Bank, 2017) defines DLT as a new and fast-evolving approach to recording and sharing data across multiple data stores (ledgers). Each data store is termed as Ledger. Each ledger has the exact same data records and is collectively maintained and controlled by a distributed network of computer servers known as nodes. In layman’s language, DLT is nothing but a distributed database with some properties.
What is Blockchain?
The Blockchain is a special type of distributed ledger technology that uses
cryptographic algorithmsto create and verify a continuously growing data-structure also referred as Block that makes a chain of such transaction blocks and thus it is termed as Blockchain.
Above diagram shows set of blocks interconnected and is ever-growing chain of blocks. This is a simplistic view of Blockchain.
What is Block?
Block is a set of validated transactions and pointing to the next block in the Blockchain or we can term it as a container data structure. It is stored at each of the node on the network (in case of bitcoin). Each block contains three items.
- Set of transactions
- hash pointer to previous block
- Header- The header contains metadata about the block. As described by (Cosset, 2017), there are three different sets of metadata as per Bitcoin Blockchain.
- The hash of the previous block – Every block N contains the Hash value of Block N-1.
- Mining competition – This contains the timestamp, nonce and the difficulty. Mining concepts are discussed in more detain consensus algorithms.
- Merkel tree root – This data structure summarizes the transactions in the given block.
- Block example in Bitcoin Blockchain network: