What is BlockChain: Full Guide for Beginners

There are lots of people who are interested in learning blockchain as it is one of the best technologies in 2020. All of a sudden we are listening to the term blockchain a lot in the IT industry. It is one of the biggest innovations of the 21st century. Currently, in the IT industry, there is a huge demand for BlockChain Developers, so if you are planning to switch your technology or planning to become a blockchain developer then this is the right time as there are lots of jobs available and companies are offering a very good salary. So, you can get a job very easily with a good salary. With platforms like Ethereum taking the lead, more and more companies are looking for BlockChain Developers who can build decentralized applications.

What is BlockChain?

Blockchain technology was introduced in 1991 by Stuart Haber and W. Scott Stornetta. In simple words, it is just a chain of blocks, where a block consists of data information and the chain is like a database. So, Suppose there is a blockchain which has 10 blocks, so each block will store some data.

Each block in a blockchain has three parts

  1. Data Information
  2. Hash
  3. Hash of the previous block

Let me explain this in more details, let us consider an example of an e-commerce store. So if you want to store the purchase details of the site in a blockchain then let me tell you how the blockchain will be implemented.

1.    Data Information

The details of the purchase made from the website, date & time of purchase, amount and say the delivery address. We need many more things to store in our blocks for an e-commerce site but as of now let us consider storing these three details only. 

So the data information part of each block will store the details (like the date & time of purchase, amount and say the delivery address) of each and every purchase.

2. Hash 

Before telling you about the Hash of the block  Let me tell you guys what is hashing. Hashing is a technique of generating value from a string of text using a mathematical function. 

So considering the above example of the e-commerce site. 
Details of 1st purchase are like
Date & time of Purchase – 19th Feb 2019
Amount – 20$
Delivery Address – 22, Delhi, India
So using a mathematical function we will be converting these details to a value and that will be known as the hash of that particular block. 
Suppose after a certain calculation done by the mathematical function, we generate the hash for this block as 1H4KK92R, then  1H4KK92R will be the Hash for this block.

And this hash will help us to identify each block as it will be unique for each and every block.

3. Hash of the previous block

This part of the block stores the hash of the previous block and this helps in keeping the blocks connected and makes a chain of blocks and this overall technology is named as blockchain.

Genesis Block
As the first block does not need to store the hash of the previous block so it is called Genesis Block.

How Blockchain is Secured

Let us talk about why blockchain is so secure that it is being used by financial companies these days

Reason 1: Hash
Blockchain technology is very secure as changing any details in any of the blocks will change its hash and we need to calculate the hash of all the following blocks. So suppose we try to change the details of block 6 then its hash will be changed and for that, we need to calculate the updated hash for block 7 and all the following blocks.

Reason 2: Proof of Work
Proof of work is basically the mechanism of slowing down the process of calculating the hash of the block and adding a new block to the blockchain. So suppose we try to tamper block 6 then we need to redo the proof of work for all the following blocks which will take a lot of time.

Reason 3: Being Decentralized

Blockchain does not store any of its information in a central location. Every user of a blockchain gets their own copy of that blockchain. Whenever a new block is added to the blockchain, every user on the network updates its blockchain to reflect the change. By spreading that information across a network, rather than storing it in one central database, blockchain becomes more difficult to tamper with. If someone tries to tamper a blockchain then he/she can only tamper a single copy of the blockchain.
So tampering blockchain is very difficult and that is the reason lots of financial institutes are implementing blockchain technology.


Blockchain technology was introduced in 1991 but it was never used by anyone. Satoshi Nakamoto first used this technology in 2008 to implement Bitcoin which is the first cryptocurrency. 

So this was the basic information about blockchain. You can watch videos on what is Blockchain in our video on YouTube channel. You can also subscribe to our YouTube channel for practical implementation of blockchain. You can also read our other blogs.

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