Assume that 4 people are called ABCD, and 3 transactions are initiated between them. A transfers 10 bitcoins to B, B transfers 5 bitcoins to C, and C transfers 2 bitcoins to D. If it is a traditional accounting method, these transactions will be recorded in the bank’s system. This information is recorded by the bank. We believe that the bank will not add, delete or modify a transaction record at will, and we will not pay attention to what transactions are actually there. We only focus on our account balance. The Bitcoin accounting method keeps such an account book for each person in ABCD. The above transaction content is recorded on the account book. If everyone's account book is consistent in real time, ABCD no longer needs a bank.
Bitcoin does this. Whenever someone initiates a transaction, he will broadcast a transaction to the entire network, and a certain person in the entire network will package and record the transaction within a period of time into a block. , And then link these blocks one by one in order to form a chain, which is the so-called blockchain.

Then the problem is coming

1. Why should I participate in this system? Why should I use my computer resources to store this information?

2. Whose record shall prevail? For example, in the above billing order, user A may be in this order, but B may be in a different order, or even B may not receive the message that C transfers money to D at all.

3. If Bitcoin achieves the payment function, it is guaranteed that the money belongs to whose money, and only its owner can spend it.

4. How to anti-counterfeit, anti-tampering and double payment. Anti-counterfeiting is to verify that each transaction is really sent by someone. For example, B may fabricate a message and say that so and so transferred a sum of money to me. This is a fake message. Or B says how much money I transferred to someone, but in fact he doesn't have that much money, what should I do? Anti-tampering means that B may want to delete the record of the money he has transferred to someone from the blockchain, so that his balance will increase. Double payment means that B only has 10 bitcoins, and he transfers 10 bitcoins to C and D at the same time, causing double spending.