The concept of blockchain was given by Stuart Haber & W.Scott Stornetta . In the Year 1991, they have published a paper researched on “How to timestamp a document?” idea of the blockchain is influenced by it.

As per Wikipedia, Blockchain is continuously growing lists of Block, linked and secured using cryptography.

So to start with, we have depicted the typical structure of a block. Block contains data, the value of Previous Hash & Its Own Hash.  Hash is a Hexadecimal code whose output is dependent on Data & Previous Hash of the block. For the time being, Let’s consider Hash is like a fingerprint of the block.

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Now let’s have a look at the blockchain. The first block in a Blockchain is always known as Genesis Block. Since Genesis Block would be the first block in Blockchain, the value of Previous Hash would be NULL. Given below is the structure of Genesis Block.

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The structure of a typical blockchain is given below. Block 2 in a blockchain is having its data, Previous Hash and its Own Hash. Technically Previous Hash of Nth Block refers to Own Hash of (N-1)th Block.

<center>![Image3.png](https://cdn.steemitimages.com/DQmaQp9feq6LyBBbFX3sZr3m988fMnmp7CRz5bF57RYbKCp/Image3.png)</center>
 
Now in a typical blockchain, if anyone tries to change the data at Block 2, its own hash will change, which will not match with the Previous Hash of Block 3, and hence the Blockchain will fail. This concept is considered very helpful in stopping fraudulent activities in Property Registration, Banking Process etc.

So that’s blockchain at very high level. In coming articles we would dig deeper into Blockchain:

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