What is Blockchain?

What is Blockchain?

Blockchain is a distributed ledger (ok but what this really mean ?). Let me explain it !

According to Wikipedia “A blockchain is a distributed ledger with growing lists of records (blocks) that are securely linked together via cryptographic hashes.” In other words, it is a list of transactions and each bundle of transactions are linked to the previous block.


Blockchain is DLT (Distributed Ledger Technology) which is immutable and distributed in nature, it stores and replicated the data in each node. To understand the Blockchain we should first understand some words.

  • Immutability

  • Distribution

  • Ledger

  • Node


Let us see this word and what it means.


Immutability means once you have written on a blockchain it can't be deleted how much you try. It is impossible to erase data from a blockchain. So, it is considered the safest data storage. In a web2 database system, we have access to the data, we can create, modify or delete the data but in blockchain, we can only add and modify data. In web2, we need to trust the authorities and hope they don't delete or modify our data without our permission, but in blockchain, we don't need to trust others to handle our data, as no third person is involved.


In Blockchain the data Is replicated and distributed to every node or host or peer, we can trust the data if most of the node is working correctly or in a valid state if a node is misbehaving the node goes to an invalid state and the node is kicked out from the network. Each node has the whole ledger or blockchain in its local storage this guarantees high availability and security as the data is easily verifiable and accessible.


Ledger is a list of transactions recorded with a time stamp and stored in a block and each block is connected to the previous block, the first block or the head block does not have a previous block so its previous block is NULL. The first block is called Genesis Block, You can check the first block of any blockchain in etherscan.io

Node ( Host or Peer)

Node is the host, server, or computer in which the blockchain program runs. Think of it as a virtual machine that runs on another OS but it allocates its own resource. Each node has a copy of the blockchain in the host. Anyone can run a node if he or she has the required configuration device. By running a node anyone can earn blockchain cryptocurrencies which can be used as money in that ecosystem.

What's on the next article?

In the next article, we will see the blockchain structure and how it works, so make sure to subscribe to the newsletter and follow me on Twitter.

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