Number of BTC blocks

1.

There are only 21 million bitcoins

"graphics card mining" is a joke. In fact, it is running a specific algorithm to generate bitcoin through a large number of calculations

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extended materials:

the concept of bitcoin was first proposed by Nakamoto in 2009. According to Nakamoto's idea, the open source software was designed and released, and the P2P network on it was constructed. Bitcoin is a kind of P2P digital currency. Point to point transmission means a decentralized payment system

unlike most currencies, bitcoin does not rely on specific currency institutions. It is generated by a large number of calculations based on specific algorithms. Bitcoin economy uses the distributed database composed of many nodes in the whole P2P network to confirm and record all transactions, and uses the design of cryptography to ensure the security of all aspects of currency circulation. The decentralized nature and algorithm of P2P can ensure that it is impossible to artificially manipulate the value of bitcoin through mass proction. The design based on cryptography can make bitcoin only be transferred or paid by the real owner. This also ensures the anonymity of money ownership and circulation transactions. The biggest difference between bitcoin and other virtual currencies is that the total amount of bitcoin is very limited and it has a strong scarcity. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to 21 million

bitcoin can be cashed and converted into the currency of most countries. Users can use bitcoin to buy some virtual items, such as clothes, hats and equipment in online games. As long as someone accepts it, they can also use bitcoin to buy real-life items

on February 26, 2014, Joe Manchin, a Democratic senator from West Virginia, issued an open letter to a number of regulatory authorities of the US federal government, hoping that the relevant authorities would pay attention to the status quo of bitcoin's encouraging illegal activities and disrupting the financial order, and demanded that actions be taken as soon as possible to completely ban the electronic currency

from 12:00 noon on January 24, 2017, China's three major bitcoin platforms officially began to collect transaction fees

2.

The concept of 21 million

bitcoin was first proposed by Nakamoto in 2009. According to Nakamoto's idea, open source software was designed and released, and P2P network was built on it. Bitcoin is a kind of P2P digital currency. Point to point transmission means a decentralized payment system

bitcoin is not issued in unlimited quantity, which is different from most currencies. Bitcoin does not rely on a specific currency issuer. But according to the specific algorithm, through a large number of calculations. Its circulation is controlled by software algorithms. The total number is 21 million

extended materials:

generation principle

starting from the essence of bitcoin, the essence of bitcoin is actually the special solution generated by a bunch of complex algorithms. A special solution is one of the infinite (in fact, bitcoin is finite) solutions that can be obtained from the equations. Every particular solution can solve the equation and is unique[ 10] In the metaphor of RMB, bitcoin is the serial number of RMB. If you know the serial number of a note, you have the note. The process of mining is to constantly seek the special solution of this equation system through a huge amount of calculation. This equation system is designed to have only 21 million special solutions, so the upper limit of bitcoin is 21 million

to mine bitcoin, you can download the special bitcoin computing tools, register various cooperation websites, fill the registered user name and password into the computing program, and then click the operation to officially start. After completing the installation of bitcoin client, you can directly obtain a bitcoin address. When others pay, you only need to paste the address to others, and you can pay through the same client. After installing the bitcoin client, it will distribute a private key and a public key. You need to back up your wallet data containing your private key to ensure that your property is not lost. Unfortunately, if the hard disk is completely formatted, personal bitcoin will be completely lost

3. Theoretically, the block reward generated every day is 12.5 (number of rewards per block) * 6 * 24 (6 blocks per hour, 24 hours per day) = 1800btc
bitcoin network generates one block every 10 minutes on average, and the reward for each block is currently 12.5. At the earliest time, 50 BTCs were awarded to each block, which was halved after 210000 blocks were excavated, about once every four years. It is expected that the next halving will be in May 2020, when the reward for each block will become 6.25
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4. Bitcoin blockchain is a bitcoin blockchain? No, the block stores the transaction. In the early stage, you will get a coin if you successfully build a block. In the later stage, you can only get the fees paid by the exchange. A currency is a string of digital signatures. It is a digital signature sent by the last owner to the receiver. Everyone can see who owns the currency from the transaction
does each node have complete blockchain data? You mean a user node? A user node needs to keep the of the block head of the longest workload proof chain, so it knows the data of all the block heads. It can move forward to know all the data on the block chain, but not all of them are saved. A block header is very small, only 80 bytes, which can be saved completely, because the generation of nodes is very slow. Even with the passage of time, the amount is not too large now.

5. Each block contains the information of all recent transactions, a nonce (random number) and the hash value of the previous block. When the SHA-256 hash value of the whole block is lower than the current target value, it is marked as "resolved" (published and verified by multiple nodes). Usually, it is difficult to achieve the goal by hashing once, so nonce must be increased, and blocks must be hashed millions of times to achieve the goal.

6. You are right. Indeed, it will be rolled back. If the transaction is unfortunately packaged on the fork, the transaction is likely to be cancelled after the main chain is synchronized

the reason why we need six confirmations is that it is more difficult to obtain the optimal solution (to prevent single node fraud). One block may also be able to get an optimal solution, and it is basically impossible to get six blocks together. It has nothing to do with bifurcation

7. Triporg travel: a travel service application using blockchain, which provides booking services such as air tickets and train tickets.

8. Bitcoin is not issued by specific currency institutions, it is generated by a large number of calculations based on specific algorithms. Bitcoin economy uses the distributed database composed of many nodes in the whole P2P network to confirm and record all transactions, and uses the design of cryptography to ensure the security of all aspects of money circulation. The decentralized nature and algorithm of P2P can ensure that it is impossible to artificially manipulate the value of bitcoin through mass proction. The design based on cryptography can make bitcoin only be transferred or paid by the real owner. This also ensures the anonymity of money ownership and circulation transactions. The biggest difference between bitcoin and other virtual currencies is that the total amount of bitcoin is very limited and it has a strong scarcity. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to 21 million