What is block chain ?
A blockchain is a database like any other database but what it contains is not controlled by anyone. It is peer-to-peer controlled.
No matter what type of data is used to pay for the network, that data will be present in all the machines operating within the network.
It was invented in 1990, but it was not so popular then. Not everyone knew about it, but It has become much more popular since 2009 when Satoshi Nakamoto helped build Bitcoin with block chain.
How blockchain is formed ?
It is usually divided into three parts
3. Hash of previous block
1. What is dada in block ?
The cipher text from which the information is contained in the block or stored in the block is called data
2.What is hash in block ?
The hash code is the mathematical algorithmic form of the information that contains the data in the block.
3. What is hash of previous block ?
Just before that blog, the block data hashcode was called the hash of previous block.
That's min the hashcode of the block just before that block is meant.
In this way each block is shaped like a chain attached to its previous blog hash code and is called a blockchain.
What is genesis block ?
The first block in a blockchain that does not contain any hashcode of a previous block is called a genesis block.
If a hacker wants to change a database, he can't do this just hack a computer and make that database change.
It is impossible for him to hack all the computers in the network and then change the database for which it is called unhackable.