What are the current blockchain public chains

3.

Public chain, also known as "public chain", refers to the blockchain that anyone in the world can enter the system at any time to read data, send confirmatory transactions and compete for bookkeeping. The public chain is generally considered to be "completely decentralized", because no indivial or institution can control or tamper with the reading and writing of data in it. In terms of application, blockchain public chain mainly includes bitcoin, Ethereum, super ledger, most counterfeit currencies and smart contracts. The ancestor of blockchain public chain is bitcoin blockchain, which has the following characteristics:

1, open source code

upload the code to GitHub, and everyone can get complete blockchain data by downloading, Accept the test of the public

2, complete decentralization

anyone can become a node, each node is open, everyone can participate in the calculation of the blockchain, any node is not permanent, but phased, and any center is not mandatory for nodes. Anyone can read and send transactions, and transactions can be effectively confirmed on the blockchain. Anyone can participate in the consensus process. The consensus process determines whether a block can be added to the blockchain and the exact current state. Everyone can get financial reward from it, which is proportional to their contribution to the consensus process. These public chains are generally considered to be "completely decentralized"

3. Developing decentralized applications

through this public chain, developers can easily develop centralized applications. Public chain can protect the rights and interests of users from the influence of program developers

4. At present, the mature application of blockchain technology is more concentrated in some public chain projects, because many application projects need to be developed based on this, so I think public chain projects are one of the major landing directions in the world. It's still too early to talk about maturity. After all, bitcoin and Ethereum are still blocked, and many old problems have not been solved, There will be many new problems. The well-known ones are Biyuan chain, ulord (the project is abroad, but the technical party provides it in the domestic company, Hunan Tianhe Guoyun Co., Ltd.), quantum chain, Xiaoyi Neo, gongxinbao, etc.

5. The public chain, as the name suggests, has great inclusiveness and fairness. The better the public chain project does in these two aspects, the more prominent it will be. At present, many public chains sacrifice fairness in order to speed up the transaction, which is not optimistic. There is a project called Fanta network. Their DSC technology claims to be safe, democratic and fair, which deserves long-term attention. However, their code will not be open source until the end of the year, and the progress needs to be accelerated

6. The goal of mitx is to build an enterprise level blockchain platform as a service (bpaas) and an affiliated blockchain application market. The essence of enterprise level blockchain is to enable all kinds of enterprises, no matter how large, to design, deploy and run distributed ledger on our platform. It can even create its own blockchain innovation laboratory, equipped with the necessary infrastructure and a complete set of integrated tools, which can realize the low-cost test drive of blockchain applications. This is a good platform for blockchain experiment and incubation
as the world's first blockchain project aimed at transforming the fashion instry and establishing a new fashion ecology, fashion planet has attracted the attention of the fashion instry and blockchain circle as soon as it appeared. Kim
Chung Ho, the South Korean technical director of the project, said in an interview: "fashion star is an organic combination of blockchain technology and fashion AI, complementing and relying on each other, giving full play to their respective functional characteristics, solving a series of pain points in the fashion instry, and realizing the transformation of the fashion instry
at present, these two projects are developing very well.

7. There are many blockchain applications now, and they are still growing<

the people's Bank of China launched the trade finance blockchain platform: widely connecting the information of tax, customs, foreign exchange and other departments, effectively helping SMEs to increase their financing credit
State Grid supply chain financial data sharing platform based on data side chain: provide conditional and reliable sharing service of supply chain financial data under privacy protection, help small and medium-sized suppliers to revitalize accounts receivable, rece financing cost and increase financial income of financial institutions
there are also Guangzhou public law chain, blockchain e-invoice Express Edition, trade finance blockchain platform, blockchain deposit, blockchain traceability and so on. Cipher finance mimacaijing focuses on blockchain information.

8. Blockchain mainly solves the trust and security problems of transactions, so it proposes four technological innovations to solve this problem:
(1) distributed ledger, that is, transaction bookkeeping is completed by multiple nodes distributed in different places, and each node records complete accounts, so they can participate in monitoring the legitimacy of transactions, At the same time, they can testify together
different from traditional distributed storage, the uniqueness of distributed storage of blockchain is mainly reflected in two aspects: one is that each node of blockchain stores complete data according to block chain structure, while traditional distributed storage generally stores data in multiple copies according to certain rules. Second, the storage of each node in the blockchain is independent and has the same status, which relies on the consensus mechanism to ensure the consistency of storage, while the traditional distributed storage generally synchronizes data from the central node to other backup nodes[ 8]
no single node can record the account data separately, so as to avoid the possibility that a single bookkeeper is controlled or bribed to record false accounts. In theory, unless all the nodes are destroyed, the accounts will not be lost, so as to ensure the security of the account data
(2) asymmetric encryption and authorization technology, the transaction information stored on the blockchain is public, but the account identity information is highly encrypted, which can only be accessed under the authorization of the data owner, thus ensuring the data security and personal privacy
(3) consensus mechanism is how to reach a consensus among all accounting nodes to determine the validity of a record, which is not only a means of identification, but also a means of preventing tampering. Blockchain proposes four different consensus mechanisms, which are suitable for different application scenarios and achieve a balance between efficiency and security
the consensus mechanism of blockchain has the characteristics of "the minority is subordinate to the majority" and "everyone is equal", in which "the minority is subordinate to the majority" does not completely refer to the number of nodes, but also can be the computing power, the number of shares or other characteristics that can be compared by computers“ "Everyone is equal" means that when the nodes meet the conditions, all nodes have the right to put forward the consensus results first, and then directly recognized by other nodes, and finally may become the final consensus results. Taking bitcoin as an example, the workload proof is adopted. Only when more than 51% of the accounting nodes in the whole network are controlled can a nonexistent record be forged. When there are enough nodes in the blockchain, this is basically impossible, thus eliminating the possibility of fraud.
(4) smart contract, which is based on these trusted and tamperable data, can automatically execute some pre-defined rules and terms. Take insurance as an example. If everyone's information (including medical information and risk occurrence information) is true and reliable, it is easy to carry out automatic claim settlement in some standardized insurance procts

9. Xiaoyi blockchain, laikelib and many others seem to be very successful.