What is blockchain technology?
We understand that blockchain relates to improved security, but how? “The whole point of using a blockchain is to let people in particular, people who don’t trust one another – share valuable data in a secure, tamperproof way.“
Here the block refers to the digital information and the chain refers to the public database. So, blockchain is actually the digital information stored in a public database. We have a number of houses in a society and we differentiate them using a number.
Here the society is the blockchain, the houses in them are the blocks and the house number is the hash code. As the house number is used to differentiate between each house, the hash code is a kind of number that is used to identify each block.
Another term to understand is the nodes which connect all the blocks. Mostly nodes are computers, laptops, big servers etc.
Now let us understand how the blockchain works consider 5 blocks in a blockchain with format name (hash code)[Previous hash code]:-
A (11aa) 
B (22bb) [11aa]
C (33cc) [22bb]
D (44dd) [33cc]
E (55ee) [44dd]
Now, here we need to know that each block has a hash code and a previous hash code from the block it is connected to which is mentioned inside . Here A does not have a previous hash code as it is the first block.
So, now we have a blockchain ABCDE. Consider the society example and now we have 3 managers namely X, Y & Z to look after society & ABCDE are the names of the houses in the society. Here each of the 3 managers has data regarding ABCDE.
Now, say if X wants to add a new block named F then the approval of Y and Z will be needed to do so. So if X wants to add F block without Y and Z’s knowledge he would have to hack into each of their computers and accept the F block to be included in the blockchain.
Now here the point to be noted is that when considering a blockchain there are multiple users, not just 2 as explained in the example. So, to tamper with the data in the blockchain hacking into all the servers that have access to it becomes next to impossible and hence this is considered great when security is of prime importance.
Also say if data is tampered with in any block, its hash code changes. Due to this the blocks following it will have a change in their previous hash code and as a result, a new hash code will generate in each of them.
This will alarm other users in the network and the tampering of data can be stopped right away. The other option is hacking into all the users involved but that is not as simple as it sounds.
If you still don’t understand how the blockchain works be sure to watch this video it has explained in simple terms on how it works. If you have already understood you may still take a look to enhance your knowledge. VIDEO LINK
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