Blockchain 100 questions 14

1.

The strict definition of blockchain refers to the distributed database technology that multiple nodes in peer-to-peer network jointly maintain a continuously growing list ledger constructed by time stamp and orderly record data blocks through consensus mechanism based on cryptography technology. This technical solution allows any number of nodes in the participating system to calculate and record all the information exchange data in the system in a period of time to a data block through cryptography algorithm, and generate the fingerprint of the data block for linking the next data block and checking. All participating nodes in the system jointly determine whether the record is true

blockchain is a technical solution similar to NoSQL (non relational database). It is not a specific technology, and can be implemented through many programming languages and architectures. There are many ways to realize blockchain, including pow (proof of work), POS (proof of stake), dpos (delegate proof of stake), etc

the concept of blockchain was first proposed in the paper "bitcoin: a peer-to-peer electronic cash system" by indivials (or groups) who call themselves Satoshi Nakamoto. Therefore, bitcoin can be regarded as the first application of blockchain in the field of financial payment

< H2 > [popular explanation]

no matter how big the system or how small the website is, there is a database behind it. So who will maintain this database? In general, who is responsible for the operation of the network or system, then who is responsible for the maintenance. If it is wechat database, it must be maintained by Tencent team, and Taobao database is maintained by Alibaba team. We must think that this way is natural, but blockchain technology is not

if we think of the database as a book, for example, Alipay is a typical account book. Any change of data is bookkeeping. We can think of database maintenance as a very simple way of accounting. In the world of blockchain, everyone in the blockchain system has the opportunity to participate in bookkeeping. The system will select the fastest and best bookkeeper in a period of time, maybe within ten seconds or ten minutes. The bookkeeper will record the changes of the database and the account book in a block. We can think of this block as a page. After the system confirms that the records are correct, the system will record the changes of the database and the account book in a block, It will link the fingerprint of the past account book to this paper, and then send this paper to everyone else in the whole system. Then, over and over again, the system will look for the next person with fast and good bookkeeping, and everyone else in the system will get a of the whole ledger. This means that everyone as like as two peas in the system is called Blockchain. It is also called distributed account technology. P>

as like as two peas (computer) have identical accounting books, and everyone has the same rights, they will not collapse e to the loss of contact or downtime of a single person. As like as two peas, the data is transparent and everyone can see what changes are in every account. Its very interesting feature is that the data can't be tampered with. Because the system will automatically compare, it will think that the same number of books with the largest number are real books, and a small number of books with different numbers are false books. In this case, it's meaningless for anyone to tamper with his own account book, because unless you can tamper with most nodes in the whole system. If there are only five or ten nodes in the whole system, it may be easy to do so. However, if there are tens of thousands or even hundreds of thousands of nodes and they are distributed in any corner of the Internet, unless someone can control most computers in the world, it is unlikely to tamper with such a large block chain

< H2 > [elements]

combined with the definition of blockchain, we think that we must have the following four elements to be called public blockchain technology. If we only have the first three elements, we will consider it as private blockchain Technology (private chain)

1, peer-to-peer network (power equivalence, physical point-to-point connection)

2, verifiable data structure (verifiable PKC system, non tampering database)

3, distributed consensus mechanism (Solving Byzantine general problem, solving double payment)

4 Game design of Nash equilibrium (cooperation is the strategy of evolutionary stability)

< H2 > [Characteristics]

combined with the definition of blockchain, blockchain will realize four main characteristics: decentralized, trustless, collective maintenance and reliable database. And the other two will be derived from the four characteristics  Features: open source  Privacy. If a system does not have these characteristics, it can not be regarded as an application based on blockchain technology

Decentralized: there is no centralized hardware or management organization in the whole network. The rights and obligations of any node are equal, and the damage or loss of any node will not affect the operation of the whole system. Therefore, it can also be considered that the blockchain system has excellent robustness

trustworthiness: there is no need to trust each other when participating in the data exchange between each node in the whole system. The operation rules of the whole system are open and transparent, and all data contents are also open. Therefore, within the specified rule range and time range of the system, nodes cannot and cannot cheat other nodes

collective maintenance: the data blocks in the system are maintained by all the nodes with maintenance function in the whole system, and these nodes with maintenance function can be participated by anyone

reliable database: the whole system will enable each participating node to obtain a of the complete database in the form of sub databases. Unless more than 51% of the nodes in the whole system can be controlled at the same time, the modification of the database on a single node is invalid, and the data content on other nodes cannot be affected. Therefore, the more nodes and computing power in the system, the higher the data security in the system

Open Source: since the operation rules of the whole system must be open and transparent, the whole system must be open source for the program

Privacy Protection: since there is no need to trust each other between nodes, there is no need to disclose the identity between nodes, and the privacy of each participating node in the system is protected

2. Do you want to learn blockchain development technology or just want to know what blockchain is? If it is the former, you can look at the code of other blockchain projects and learn about it first. If it is the latter, we can pay attention to some good blockchain we media. Blockchain is an emerging instry. There is no ready-made training course. It depends on self exploration and understanding.

3. The transaction cost of bitcoin is generally between 0.0001-0.0005btc. Of course, the amount accepted by each miner and miner's Association is different. Sometimes, a large amount of bitcoin transaction does not need a service charge, such as more than 100btc. Small transactions below 0.01btc will be charged a certain amount of fees. Of course, some bitcoin clients can set bitcoin transaction fee. If you set the transaction fee very low, the transaction confirmation time will be very long
first of all, we should understand that this service charge is given to miners to encourage them to continue mining and provide enough computing power for bitcoin, so as to ensure the security of bitcoin network. At present, the main income of miners is to get BTC reward by creating new blocks, but the reward is halved every four years. As time goes on, bitcoin transaction fee will graally replace bitcoin reward
under what circumstances should the handling charge be paid? What's the amount

bitcoin system has a series of network rules, including the handling charge rules, which are "what the client should do". When you use bitcoin client (wallet, bitcoin QT) to send bitcoin, the whole process is roughly divided into the following steps:

1. Prepare the bitcoin you want to send

the client is responsible for collecting the balance of bitcoin in your wallet (bitcoin QT) to prepare for payment, Because every bitcoin you receive is in your wallet until you spend it

if you withdraw 3btc and 2btc twice in okcoin bitcoin, their records in your wallet are independent, that is, a 3btc and a 2btc, instead of merging them into 5btc (the wallet only records transaction details, but does not merge the balance, but you can see the total balance on the interface of the wallet), As time goes on, you will accumulate a lot of bitcoin in your wallet. It is conceivable that there should be thousands of such records in okcoin bitcoin wallet. So when you send bitcoin, the wallet must decide which of the above records are most suitable for this sending

the bitcoin you get in a transaction is called "inputs" and the bitcoin you spend is called "outputs". There are multiple inputs and outputs in your wallet

2. Prevent a large number of micro payments from impacting the network

if you recharge the okcoin bitcoin trading platform less than 0.01btc (including the fund changes inside your wallet), you must pay a handling charge of 0.0001. When preparing your payment amount, the wallet has an established rule, that is, when preparing the payment amount in many inputs, try to avoid the amount change less than 0.01btc (for example, if you want to recharge 5.005btc to okcoin bitcoin, the wallet should choose 3 + 2.005 or 1 + 1 + 3.005 instead of 5 + 0.005)

3. The larger the amount, the higher the age of the currency, the higher the priority

if the amount you send is too small or your bitcoin has just been mined, then your transfer is no longer free. Each transaction will be assigned a priority, which is determined by the degree of currency, the number of bytes and the number of transactions. Specifically, for each input, the client will first multiply the number of bitcoins by the time they exist in the block (currency age, age), and then divide all the procts by the size of the transaction (in bytes). The calculation formula is: priority = sum (input)_ value_ in_ base_ units * input_ age)/size_ in_ If the calculation result is less than 0.576, then the transaction must pay the handling fee. This is why you need to add a 0.0001 when you withdraw with okcoin bitcoin, because the bitcoin transfer in okcoin wallet is frequent, and the time of bitcoin in the block is relatively short, so you need to pay a handling charge. If you do have a large number of small inputs, such as small miners, and want to transfer them out for free, you can add a large amount of bitcoin with a large currency age, and the average priority will be increased, so that bitcoin can be transferred out for free

4. Charge per kilobyte

at the end of the transfer, the client calculates the size of the transfer (in bytes), which generally depends on the amount of input and output. The calculation formula is as follows: 148 × Input amount + 34 × Output amount + 10. If the size of the transfer exceeds 10000 bytes, but the priority meets the free standard, you can still enjoy the free transfer, otherwise you need to pay the handling charge. The cost per 1000 bytes is 0.0001btc by default, but you can also add it in the client by opening the tab "settings & gt; Options & gt; The main purpose is to adjust the handling charge. If the service charge you are setting is less than 0.0001, BTC is calculated as 0.0001. When this rule applies, it will replace the rule in step 2 instead of accumulating.

4. Eosinophils are eosinophils
EOS% refers to the percentage of eosinophils in the total number of white blood cells, the normal value is 0.5% - 3%< 1. Eosinophilia:
(1). Allergic diseases: bronchial asthma, drug allergy, urticaria, food allergy, angioneurotic edema, serum diseases and other peripheral blood eosinophilia can reach more than 10%
(2). Parasitic diseases: schistosomiasis, Ascaris lumbricoides The number of eosinophils in blood, such as hookworm disease, is usually 10% or more. The number of eosinophils increased significantly in some patients with parasitic infection, resulting in the total number of white blood cells reaching tens of thousands, more than 90% of which were eosinophilic leukemoid reaction
(3) skin diseases such as eczema, exfoliative dermatitis, pemphigus, etc The eosinophils in peripheral blood of patients with psoriasis were slightly or moderately increased
(4). Hematological diseases such as chronic myeloid leukemia, eosinophilic leukemia, lymphoma, multiple myeloma, eosinophilic granuloma, etc. the eosinophils in peripheral blood were increased in different degrees, Some malignant tumors: some epithelial tumors such as lung cancer can cause eosinophilia
(6). Some infectious diseases: most eosinophils decrease in acute infectious diseases, but increase in eosinophils in scarlet fever
(7) Hypopituitarism, allergic interstitial nephritis and so on are often accompanied by eosinophilia
2. EOSINOPENIA:
it is common in the early stage of typhoid fever, paratyphoid fever, major surgery, burn and other stress states, or after long-term application of adrenocortical hormone, and its clinical significance is very small
please take it if you are satisfied
wish you good health

5. The bitcoin system can adjust the difficulty coefficient to ensure that bitcoin will not be g out too quickly
in order to ensure the stability of bitcoin and dig out a block in about 10 minutes, Nakamoto Tsung designed that the difficulty of getting bitcoin from miners mining should be dynamically adjusted every 2016 blocks (about 2 weeks). After the adjustment, the expected time for each block to be generated is 10 minutes. Now the difficulty factor is about 480ph / s. With the current computing power, the miners in the whole network need to go through about 300 trillion hash operations to find a qualified answer and generate new blocks.

6. In Himalayas, Lao Wang talks about finance, which is easy to understand

7. At the beginning, I asked 100 questions about blockchain. The video explanation was very clear. After watching each episode, I would have a general understanding of blockchain. Now I will read some official account articles and block chain media websites, etc., to understand the daily information market. Some public official account has dry cargo, which teaches you all kinds of conceptual things, including the popular DAPP, and how to play and how to create wallet. You can go to see dappdiscover.

8. Renjia times security is a technology company in Shenzhen that provides the underlying infrastructure services of blockchain technology, mainly providing services such as wallet system and security audit for enterprises and transactions. To put it bluntly, it's a technical service company. It can't issue money. ha-ha

9.

Bitcoin (abbreviated as BTC) is a point-to-point, decentralized digital asset proposed by Nakamoto (alias); In 2009, Nakamoto Cong packaged the first block and won 50 bitcoin mining awards, which are halved every four years. According to this calculation, bitcoin is expected to be issued in 2140, with a total of 21 million

do you understand what bitcoin is now? If you don't understand, just continue to look down ~ "blockchain 100 questions" makes you a blockchain brick~

10. To put it simply, in the past, transactions were accounted by third-party platforms (Taobao, Jingdong, etc.), and blockchain kept a of this account book for each party (consumers, businesses, third-party platforms), so there was no way to go back on it, and there were more layers of protection
let's give an example. For example, in our usual online shopping, after placing an order, our money will be transferred to the intermediary platform of the third-party payment agency. After the seller delivers the goods and the buyer confirms the receipt of the goods, the buyer will inform the payment agency to transfer the money to the seller's account
however, the transaction mode supported by blockchain technology is different. Buyers and sellers can trade directly without any intermediary platform. After the transaction between the buyer and the seller, the system publishes the transaction information in the form of broadcast, and all hosts receiving the information record the transaction after confirming that the information is correct, which means that all hosts have done data backup for the transaction. If there is a problem with the orders proced by this machine, its data information will not be affected, because there are countless machines backing up data at the same time.