I can't understand blockchain all the time

2. Give you an easy to understand example, you can quickly understand what blockchain is:
in a village, a spent 3000 yuan to buy a cow of B, how to record this account
so a and B found a mutual trusted C to record the account, but later a and C colluded and did not admit that a had bought B's cattle, so the deal became rough and disputes continued
later, B had another cow. Of course, B didn't sell it to a this time, because a had no credit, so he gave it to d. This time, instead of looking for witnesses, they went to the whole village to roar after the transaction. B said Wang Erhua paid 3000 yuan to buy a cow from me, d also went to the whole village to shout that I paid 3000 yuan to buy a cow from B, so there were many people in the village to record the transaction. In this way, there will be no bad debts, which is called decentralized and distributed accounting
here comes the problem
when you yell, are the villagers willing to charge for you, just because you have a big face
therefore, the first person to record accurately will get some bitcoin rewards
someone asked, what if two people finish the first record at the same time
in order to avoid this problem, it is necessary to set rules, for example, to answer a question first, or to record with feet, and it must be written in block letters. If you set a series of rules, there will not be many firsts
in the network, there are a lot of transactions going on every day, and there are also many people recording, and finally they get the reward of bitcoin. This process is the legendary mining
Mining requires a lot of equipment. We call these computer equipment mining machines
in this way, all the processes are in one system. The system will encapsulate the data every 10 minutes to form a box full of data, which we call blocks
with the continuous generation of blocks, they are linked together to form a blockchain.

3.

blockchain is a decentralized distributed ledger database . The advantage of this distributed ledger is that buyers and sellers can trade directly without any intermediary. Everyone has a backup, even if you lose this, it will not be affected

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extended data:

blockchain application field

1, financial field

blockchain has potential huge application value in international exchange, letter of credit, equity registration, stock exchange and other financial fields. The application of blockchain technology in the financial instry can save the third-party intermediary link and realize the point-to-point direct docking, so as to greatly rece the cost and quickly complete the transaction payment

2. The Internet of things and logistics

blockchain can also be naturally combined in the field of Internet of things and logistics. Through blockchain, we can rece logistics costs, trace the proction and delivery process of goods, and improve the efficiency of supply chain management. This field is considered as a promising application direction of blockchain

3. The data stored on the public welfare field

blockchain is highly reliable and tamperable, which is naturally suitable for social public welfare scenarios. The relevant information in the public welfare process, such as donation project, collection details, fund flow, recipient feedback, etc., can be stored on the blockchain, and can be made transparent and public, which is convenient for social supervision

4. In the field of insurance

in terms of insurance claims, insurance institutions are responsible for fund collection, investment and claims settlement, and often have higher management and operation costs. Through the application of smart contract, there is no need for the applicant to apply or the insurance company to approve. As long as the claim conditions are triggered, the automatic claim settlement of the policy can be realized

4.

Let's suppose villagers Lao Wang and Xiao Li. Lao Wang borrowed some money from Xiao Li, who wrote it in an IOU signed by both parties. A few days later, Lao Wang denied the existence of borrowing money and claimed that Xiao Li forged the paper. Xiao Li can't argue because he finds it difficult to prove that Lao Wang actually owes him money

in this example, Lao Wang and Xiao Li are two nodes

now assuming the same scenario, there are many pairs of people trading with each other in the village. The only evidence for each pair is the IOU. If one party fails, it will be difficult to do so. Seeing this scene, the village head came up with a solution. He suggested using a common notebook for the whole village to record all the transactions. Due to the high prestige of the village head, the villagers unanimously decided to let the village head keep this important transaction book. Each transaction, the villagers go to the village head's home, let the village head witness and record, each transaction is written into a notebook, and then safely saved. That notebook can be called a database

because this notebook is very important, the village head locked it in the safe. However, there are always some problems. Sometimes, the village head will accidentally sprinkle ink on the paper, making some transaction records illegible. This is called a single point of failure. The thief knows that there is an important notebook in the safe of the village head's house. He tries his best to steal it. This is called hacking

until one day, the village head's son owed others a lot of money, so the village head secretly deleted his son's debt entry. In this way, the village head's son "does not owe money."

when the villagers knew this, they began to question the fairness and authority of the village head. So some people put forward a new idea:

abolish the power of the village head, which is called decentralization. Let all villagers keep a notebook, and the transaction records are copied and distributed, which is called distributed database. Therefore, if there are n people in the village, there are n notebooks, that is, n nodes. Every time there is a trade between any two people, all the people in the village get together and record it in their notebooks. And no one can cover the sky. This is called decentralization

they also decided that they would never delete the mentioned transactions from their notebooks, which is irreversible. For example, Lao Wang borrowed a sum of money from Xiao Li before, but in the twinkling of an eye, he wants to return the money. Then the transaction book will not delete the previous borrowing record, but write a new repayment record, so there are two records

next, let's try to break this rule. What if we bribe Lao Wang to change his notebook? It's not feasible, because the next time the villagers meet, they find that Lao Wang's notebook is different from everyone else's, so the villagers notice that Lao Wang may be engaged in an indescribable transaction, and decide to abolish Lao Wang's transaction record and kick Lao Wang out of the organization

What if you try to bribe all the villagers? It's too expensive

the characteristic of this model is that greedy people need to pay a lot to attack the rules. He will find it more profitable to follow the rules

a smart child in the village suggested that each transaction data be called "block" and linked into a "chain" in chronological order, which is called blockchain