What's the meaning of a 2x after BTC

2. In order to understand the technical principle of bitcoin, we need to understand two important cryptographic techniques: hash code: it converts a long string into a fixed length string, and its conversion is irreversible, that is, it is impossible to guess the original string from hash code. Sha256 is mainly used in bitcoin protocol
public key system: corresponds to a public key and a private key, keeps the private key in the application and publishes the public key. When Party A transmits information to Party B, it can use Party A's private key to encrypt the information, and Party B can use Party A's public key to decrypt the information, so as to ensure that the third party cannot impersonate Party A to send the information; At the same time, when Party A transmits information to Party B, it is encrypted with Party B's public key and sent to Party B, and then Party B decrypts it with his own private key, so as to ensure that the third party cannot eavesdrop on the communication between the two people. RSA is the most common public key system, but the lliptic curve digital signature algorithm is used in bitcoin protocol. What's the difference between cash and bank account? Bitcoin is an electronic currency in BTC. In this article, it is also used to refer to the whole bitcoin system. Like opening an account in a bank, the corresponding concept in bitcoin is address. Everyone can have one or more bitcoin addresses, which are used to pay and collect money. Each address is a string that starts with 1. For example, I have two bitcoin accounts, and. A bitcoin account is uniquely determined by a pair of public key and private key. To save the account, you only need to save the private key file. Unlike bank accounts, banks keep all transaction records and maintain the book balance of each account, while bitcoin's transaction records are jointly maintained by the whole P2P network through a pre agreed protocol. How much money is in my account address? Although the current account balance can be seen by bitcoin software, unlike banks, there is no place to maintain the book balance of each address. It can only calculate the account balance in real time through all historical transactions. How do I pay? When I pay from address a to address B of the other party, the payment amount is e. at this time, both parties will announce the transaction information to each network node, telling address a to pay to address B, and the payment amount is e. In order to prevent the third party from forging the transaction information, the transaction information will be encrypted with the private key of address A. at this time, the network node receiving the transaction information can use the public key of address a to verify that the transaction information is indeed sent by address a. Of course, trading software will help us do these things, we just need to input the relevant parameters in the software. What will the network node do after receiving the transaction information? This is the most important part of the bitcoin system, which needs to be elaborated. For the sake of simplicity, only bitcoin protocol has been implemented. In the current version, each network node will save all transaction information synchronously. There are two kinds of transaction information in history, one is & quot; Verified & quot; The transaction information, that is, the verified transaction information, is stored in a series of "blocks". Each & quot; block" Is the previous & quot; bock" The ID of each block is the hash code of the hash code of the block and the new transaction information (see an actual block). The other category refers to those who also & quot; Unverified & quot; The transaction information just paid above belongs to this category. When a network node receives new unverified transaction information (possibly more than one), it can calculate the book balance of each address at that time because the node keeps all the transaction information in history, so it can calculate whether the transaction information is valid, that is, whether there is enough balance in the payment account. After eliminating the invalid transaction information, it first takes out the last & quot; block" Then, the unverified transaction information is combined with the ID, and a verification code is added to form a new "block". It needs a lot of calculation to build a new block, because it needs to calculate the verification code, so that the above combination becomes a block, that is, the first several bits of the hash code of the block are 1. At present, the first 13 bits need to be 1 (generally, the specific method is uncertain), which means that if the block is generated by enumeration method, the average number of enumerations is 16 ^ 13. Using CPU resources to generate a block is called "gold mining", because the proction of the block will get a certain reward, and the reward information has been included in the block. When a network node generates a new block, it will broadcast to other network nodes. However, this network block may not be accepted by the network, because it is possible that other network nodes have proced the block earlier. Only the earliest block or the block with the largest number of subsequent blocks is valid, and the remaining blocks are no longer used as the initial blocks of the next block. How does the other party confirm that the payment is successful? When the payment information is distributed to the network node, the network node begins to calculate whether the transaction is valid (that is, whether the account balance is enough to pay), and attempts to generate blocks containing the transaction information. When six blocks (one direct block and five subsequent blocks) contain the transaction information, the transaction information is considered "verified", so that the transaction is formally confirmed, and the other party can confirm the successful payment. A possible problem is that I will pay the balance of address a to address B, and at the same time pay to address C. If I only verify that the single comparison transaction is valid. At this point, my way of cheating is to generate six blocks including B to B and six blocks including C to C before the truth is revealed. Because I need a very long CPU time to generate a block, compared with the whole network, the probability of my cheating success is very small. What is the motivation of network nodes to proce blocks? As can be seen from the above description, in order to make the transaction information effective, the network node needs to generate 1 and 5 subsequent blocks to contain the transaction information, and such block generation is very CPU intensive. How to let other network nodes help to proce blocks as soon as possible? The answer is very simple. The agreement stipulates that BTC will be rewarded for the address where the block is proced, as well as the Commission promised by both parties. At present, the reward for procing a block is 50btc, which will be halved every four years in the future. For example, the reward will be 25btc from 2013 to 2016. Is the transaction anonymous? Yes, and No. All bitcoin transactions are visible. We can check all transaction records of each account, such as mine. But what's different from the banking monetary system is that everyone's account itself is anonymous, and everyone can open many accounts. In general, anonymity is not as good as it claims. But bitcoin has another advantage in doing black market trading: it can't be frozen. Even if the police trace a bitcoin address, there is nothing they can do unless they trace the computer used by the exchange based on the Internet address. How to ensure that bitcoin does not depreciate? Generally speaking, in the case of equivalent trading activities, the value of money is inversely proportional to the amount of money issued. Unlike the traditional money market, the central bank can determine the amount of money issued. Bitcoin does not have a central issuing institution. Only by procing blocks can we get a certain amount of BTC currency. Therefore, bitcoin's new amount of money depends on: 1. The speed of procing blocks: bitcoin's agreement stipulates that the difficulty of procing blocks is fixed at an average of 2016 every two weeks, about 10 minutes. Moore's law of doubling CPU speed every 18 months will not speed up the proction of block. 2. The number of rewards for block proction: at present, 50 BTC is awarded for each block proced, which is halved every four years. In 2013, 25 BTC is awarded, and in 2017, 12.5 BTC is awarded. Considering the above two factors, bitcoin's currency issuing speed is not controlled by any single node in the network. Its protocol makes the currency stock known in advance, and the maximum stock is only 21 million BTC

3.

TEDA coin (usdt) is a token launched by tether company, which is based on the stable value currency US dollar (USD). 1 usdt = 1 US dollar. Users can use usdt to exchange 1:1 with USD at any time

tether company strictly abides by the 1:1 reserve guarantee, that is, every usdt token issued, its bank account will have a capital guarantee of $1. Users can query funds on the tether platform to ensure transparency

{rrrrrrr}

extended data:

the functions of usdt are as follows:

1. Avoiding the overall risk of decline

in currency trading, there are three common situations, taking LTC / BTC trading as an example:

after buying LTC with BTC, BTC and LTC are both rising, and you enjoy two profits

after buying LTC with BTC, BTC and LTC will rise and fall one by one. Your income depends on the rise and fall of the two currencies, which is bigger. Only if the increase of any one is greater than the decrease of the other, can we make money. Anyway, it's a loss. If the fluctuation is equal, there will be no profit or loss

after buying LTC with BTC, both currencies are falling in extreme market, so you need to bear two losses. This is often the most frustrating

but with usdt, when the currency price falls, you can immediately change the currency into usdt, so as to ensure that your assets will not shrink

The reverse operation of digital currency withdrawal is very simple. Usdt company says that investors can transfer US dollars to the bank account of tether company through swift or exchange usdt through bitfinex exchange

if you make a lot of profits and want to withdraw cash, you can first convert your currency into usdt, and then convert it into US dollars through tether or other platforms. Here you can find that if you complete the authentication of usdt company, you can trade directly on other currency trading platforms that do not need authentication, and you do not need to authenticate other platforms again

4.

In the digital currency market, the X after each coin represents an unknown probability of a growth value of each bitcoin; Digital currency is usually issued and managed by developers and accepted and used by members of a specific virtual community

The digital representation of value is not issued by the central bank or authority, and has nothing to do with fiat money, but because it is accepted by the public, it can be used as a means of payment, or it can be transferred, stored or traded electronically

At the present stage, digital currency is more like an investment proct, because there is no strong guarantee institution to maintain its price stability, and its value measurement function has not been shown, nor can it be used as a means of payment. As an investment proct, digital currency cannot develop without trading platform, operating company and investors

extended information:

features of digital currency:

low transaction cost: compared with traditional bank transfer, remittance and other methods, digital currency transaction does not need to pay fees to a third party, and the transaction cost is lower, especially compared with cross-border payment, Cross border payment to payment service providers costs more

fast transaction speed: the blockchain technology used in digital currency is decentralized, and it does not need any centralized institutions such as clearing center to process data, so the transaction processing speed is faster

high anonymity: in addition to the physical form of money intermediary participation can achieve point-to-point transactions, one of the advantages of digital currency compared with other electronic payment is that it supports remote point-to-point payment, it does not need any trusted third party mediation, and both parties can complete the transaction in a completely unfamiliar situation without mutual trust, which is higher anonymity

5. Intercommunication, can use these several currencies to purchase the corresponding currency in front!

6. The teacher is very serious, ha ha, but don't ask questions in class. The next day, they will come out the courseware of the day before, which can be downloaded to learn. Generally speaking, they are a group of people who work hard.

7. There are three situations:
1. Segwit2x completes the hard fork upgrade, that is, the 1m block becomes 2m. And most of the computing power of the whole network supports the upgraded btc1 (or the compatible version of btc1), so that BTC maintains a chain
2. The segwit2x hard fork failed, and the BTC continued to maintain the 1m block size. Most of the computing power of the whole network runs on the node version that is not upgraded, such as bitcoin core 0.15, so that BTC maintains a chain
3. Segwit2x hard bifurcation is successful, but it splits into a new chain, namely two chains. Btc1 and bitcoin core 0.15 are supported in the whole network. It's the old 1m blockchain. And the new 2m blockchain. At present, both miners and developers hold opinions on both sides. I don't know the specific support. Users are currently in the melon eating crowd
in my opinion, in the first case, the best way is to complete the hard fork upgrade and get the support of computing power
the worst case is the third. Because in the end, a chain will die. When a chain dies, all the transactions generated in the chain will be lost, which will lead to most people losing money
the second situation has nothing to say.

8. You don't feel safe. You can do a new one and cancel the old one. Or change the old payment password.

9. It depends on what the black spot is,

10. I haven't seen it in the book center, but it's better to buy books online.