What is Blockchain (simplest definition)

B  L  O  C  K  C  H  A  I  N

 "Blockchains are digital ledgers and can be formally defined as a 

continuously-growing list of records that are linked tougher and 

secured using advanced cryptography. In more simple terms, a 

blockchain is literally a chain of blocks. Each record in the list of a 

blockchain’s chain is called a block that contains specific types 

and pieces of information. Each block will usually include some 

sort of pointer as a link to the previous bock, transaction data, and 

a timestamp, which can take a variety of forms.

Another way to look at is that a blockchain is much like a 

database where each entry is linked to the previous and next 

entry. This means that the information contained within the 

blockchain can't be changed, once a block with specific data is 

added to the chain. Depending on the chain that you are looking at, there are often useful tools for exploring that will allow you to 

scan the transaction data".

I'll try as hard as possible to explain Blockchain with any simple words or term, I can use. 

Many people keeps asking what is Blockchain? Or what is Blockchain technology? Since the advent of this 'project' it has created a whole lot of mystical ideas, or left them thinking wide about what it is really all about. However, we would be looking into it, to break up the bones of its incomprehension. 

Before we dive into it, I think it would be far much better that we use examples or instances that'll  help in giving us a clearer picture of what we're talking about. 

We should've use numbers for the description, but I suggest we'd better make use of general ideas or real-world examples. So let's go with alphabetical letters. 

We all know that the English alphabets consist of 26 letters; e.g A, B, C...Z. 

Now we go with this. 

Let's assume that the letters A-Z are names of 26 friends, the letters are 26 in number. Let's assume they stays together in a given area or city, though they might not be living together, they lives in their various house. This group of 26 friends are bid with trust, sincerity and truthfulness within themselves. They has a ritual to share truthfully share any information that comes to any of them. They provides a Walkie-talkie for themselves, for the passage of any information as it arrives. While they all have they different Record Book that each and is obligated to write down the information as they are being sent across. They adheres to this.

For instance 

C bought a wrist watch from Y at the cost of $100, on a given date(let's say on 30/08/20). Immediately the transaction is completely processed and done, the information will be sent across to the rest of 24 others while they all take notes of the transaction in their various diaries. Hence the both parties (C&Y) ascertains ascertains and confirms the transaction to the rest of others. 

With this everyone in the 26 group of friends knows that on such date, the two parties initiated a transaction, while they all agreed to that with cordiality between them. 

Let's assume this,

After 3 months from the transaction date, Y thought of acting against the rules that governs the group, and decide to break the his own part part of commitment, and chooses to act different. He went to the page that he wrote the details of the transaction and tear it off. He went to C 's house, and on seeing the wristwatch that he sold to C, he pretended to not have sold the commodity to C. While he pretended to have been looking for the wristwatch for a couple of months. Then he requested that C should give the wristwatch back to him. 

C tried explaining to him that he was the one that sold it to him but he refused while denying ever making such transactions with anyone. (otherwise he would've written it his own record book). 

It shoot up an argument between the two friends.

In this idea, we can understand that there's no how Y can deny ever making such transactions. Rather he might try to deny that but cannot convince others to. 

The attention of others will be called, while they will come over with their various record books to prove that such transactions was executed by the two parties on a date which they all noted down. 

In this situation, even if Y succeeded in convincing seven others from the group to stand for him (while they do as Y, by tearing off the page), it cannot be possible because the remaining 20 will not agree with that. Meanwhile, it is easy to manipulate 6 people than 20 people. 

In this situation, it will be almost impossible to lie or deny or manipulate an information exchanged in the past, within the network. Because even if 5 or 8 lies or denies any accurate past events, the remaining 21 or 19 can deny such fraudulent claim. Hence for a fallacious or fraudulent information to take place, half of the group has to agree on lying (majority carries the vote). But, it is very very hard to occur in such group of truth-bonded  people to convince half of the group to lie against a truth.

Such is a Blockchain network, that is how it works. The Blockchain network is just like how any network works(Internet, VPN, LAN etc). It has digital devices like computers, laptops, mobile phones etc, on as part of their network. The various parties that partakes in this network, store every information that is being transmitted in the network (Just like the transaction details that is  being recorded in the various record books). The information cannot be modified or deleted when stored. (In our illustrations above, we can understand that there's the impossibility of the transaction details being deleted, even if one person does, the information is still recorded in the fellows store. Especially, the upper-store that's the brain, if Y forgets, others will not). This happens because everyone in the network stores the same information and they approves of every transaction going on the network. Everyone makes the network possible, and it is not owned or stored by a single person, rather it is decentralized. The information shared are not centralized to only a single place, but goes to every partner's store in the network. The information shared is decentralized to in the network. 

In the illustrations above, we can imagine the following; 

*The impossibility of the information being manipulated, denied or deleted. 

*The general contribution and acknowledgement of every information being shared. 

*The possibility of fraudulent activity from anyone in the group being terminated by others. And it's denial by others.

Blockchains are resistant to being modified because of their 

inherent design. This allows blockchains to record transactions 

between different parties efficiently. These transactions are not 

only verifiable but permanent as well. Once information is 

recorded in a blockchain, the data cannot be altered after-the-fact 

without altering the subsequent blocks by having the majority of 

nodes on the network agreeing to the change.

This inability to change the data within a blockchain make illegal 

or unfair actions almost impossible to carry out. If a hacker wished 

to alter information within a blockchain, they would have to gain 

control of every node. This security is one of the most useful 

characteristics of the blockchain.

Since blockchains are designed to be verifiable and permanent, 

they are especially suitable for recording events, maintaining 

medical records, drawing up agreements, fundraising, and 

keeping track of other documents.

Important points:

1. A Blockchain is a type of diary or spreadsheet containing information about transactions.
2. Each transaction generates a hash.
3. A hash is a string of numbers and letters.
4. Transactions are entered in the order in which they occurred. Order is very important.
5. The hash depends not only on the transaction but the previous transaction's hash.
6. Even a small change in a transaction creates a completely new hash.
7. The nodes check to make sure a transaction has not been changed by inspecting the hash.
8. If a transaction is approved by a majority of the nodes then it is written into a block.
9. Each block refers to the previous block and together make the Blockchain.
10. A Blockchain is effective as it is spread over many computers, each of which have a copy of the Blockchain.
11. These computers are called nodes.
12. The Blockchain updates itself every 10 minutes.