The most attractive application of blockchain is undoubtedly represented by "Ether", which uses blockchain to make a "global computer", and then uses "smart contracts" to write software (also known as "Dapp", i.e., decentralized application) that runs on this global computer. Then, "smart contracts" are used to write the software (also known as Dapp, i.e. decentralized application) running on this global computer. Simply put, the benefit of this global computer is that you can move everything you want to "cut out the middleman to make a difference" to do it all, without relying on a large enterprise as a trusted center, such as banks or Internet giants.

Business operations rely on information. The faster the information is received and the more accurate its content, the better it is for business operations. blockchain explore is ideal for delivering this information because it provides instant, shared, and fully transparent information that is stored on a non-tamperable ledger that can only be accessed by licensed network members. Blockchain networks can track information about orders, payments, accounts, production, and more. Because a single trusted view is shared among members, you can take an end-to-end approach to see all the details of a transaction, resulting in increased confidence, efficiency, and new opportunities.

However, this vision of a global computer in the past two years has exposed a lot of problems, so people do not see the hope of short-term solutions. Thus, the application direction revealed in the blockchain news this time, "untamperable" the characteristics of the blockchain, and its role in the deposit, traceability, anti-counterfeiting, credit, and so on. This is the most mature application in the field, and it is also the application that can show the advantages of blockchain compared with the traditional centralized system.

There are many aspects of blockchain-related technologies, which I can roughly divide into four categories: 1) consensus algorithms; 2) privacy protection technologies and corresponding cryptography technologies; 3) smart contract-related technologies; and 4) application-oriented related technologies. Among them, the first three can be considered as the bottom layer and the last two as the top layer.

1) The consensus algorithm is the core of the blockchain, and also the most enthusiastic area of the whole technology development and academia: a large number of public chain projects are pursuing the innovation of consensus algorithm, and at the same time, a large number of researchers are also devoted to this field, however, mostly in foreign countries (my previous main research direction is also in this field). This is not a surprise - as we all know, few people in China are willing to engage in basic theory research.

But the consensus algorithm covers a very wide range of consensus algorithms, and one of the concepts is very important - licensed and unlicensed, licensed consensus algorithms require that the identity of all participating nodes is known, the main use of class BFT algorithm. The permissionless consensus algorithms, on the other hand, allow any node to enter as long as it meets certain conditions, without having to register its identity in any system beforehand, and POW and the later derived POS and many other POx-like algorithms are included in this list. The former, are mostly used in federation chains, while the latter are mostly used in public chains. Among them, the development of the two to today, in the speed and latency of the difference is no longer very big, it comes down to the difference is the aforementioned difference between the presence or absence of a license. The permissionless consensus algorithm, due to the characteristics of the permissionless consensus algorithm, leads to a very important concept called "incentive mechanism", such as the mining of Bitcoin, and then derived from the "currency". As a result, there are many interesting directions, such as ASIC mining, on-chain governance, crypto-economics, and so on.

2), the cryptography technology used in blockchain technology itself is not profound or complex, just hash functions and digital signatures, which are two very classic and simple cryptography tools. However, due to the inherent fit between blockchain technology and cryptography (most of the early researchers in blockchain came from the field of cryptography), and because the word "cryptocurrency" is not the word commonly used in the Chinese field, but rather the term "cryptocurrency", which is used to refer to all the currencies similar to Bitcoin. (note: in English, this term is used to refer to all currencies such as Bitcoin, not "digital currency" as is commonly used in Chinese), leading most people to believe that cryptography is inherently linked to the blockchain.

Blockchain technology itself does not use particularly advanced cryptographic tools (although some new consensus algorithms have adopted some new cryptographic tools). However one of the most important cryptographic challenges is privacy-preserving technology, and among the things that might be used are cryptographic tools that are currently under development, including zero-knowledge proofs, homomorphic encryption, and so on. This is not a need for blockchain per se, but is tightly linked to blockchain - for reasons that go back to the nature of blockchain and blockchain applications before:

First of all, the biggest feature of blockchain is that all data on the chain must be verified by all nodes, however, if blockchain gets massively adopted, this means that all nodes will have access to all data. Well, a big part of the reason we don't trust the center now is that the center has access to all of our data, and now, after decentralization with blockchain, everyone has access to all of our data.

So how can we be able to guarantee privacy while still enjoying the benefits of decentralization that blockchain brings? This requires all nodes to be able to verify the validity of the data without knowing the content of the data, e.g., without knowing who you are, exactly how much money you have, and how much you want to spend, verify that you do have a sum of money available to fulfill this expenditure ......

3), smart contract-related technologies, actually including languages, including compilation ...... These amount to the question of how to use the blockchain when we already have it as the underlying layer. There's not a very clear direction on this at the moment because there are a couple of ideas that are currently being tried.