In view of the fact that many people on the Internet media have explained the practice and difference of Layer 2 technology in detail from a technical point of view. This article will explain layer2 in layman's terms.

issue concerned:

• Why is layer2 needed?
• If the expansion of layer1 is successful, is layer2 still needed?
• What is the impact of the successful practice of layer2?
• What are the hot projects in layer2?

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The necessity of Layer2

Does layer2 refer to the layer2 of Ethereum?

First of all, many public chains can be layer 2. It's not that only Ethereum has layer2. layer2 is the basic protocol network, for example, the Ethereum mainnet is layer1.

Why doesn't layer2 of other projects seem to be very popular? When you say layer 2, what you think of is the layer 2 of Ethereum?

Because most of the public chain layer1 is not good, the foundation is not solid, how to build a house. Simplified understanding is that layer1 is the asphalt road in daily life. Because of the large flow of people, viaducts, flyovers, underground passages, etc. are needed. These viaducts and other facilities are layer2. Solve the expansion problem.

Does that mean that after ETH2.0, there is no need for layer2?

no. After the expansion of Ethereum 2.0, the PoS mechanism is adopted, and the TPS can reach more than 3000, which also requires layer2. Although Xiao Feng (Wanxiang Blockchain) and other industry experts have said that the blockchain field is different from credit cards and Alipay in that settlement and transactions are completed at the same time, even 3000TPS can already meet the needs. However, this is just a self-consolation of insufficient performance. No matter how high the TPS is, as long as the number of users of the blockchain is increasing, as long as the number of humans on the earth is increasing, the expansion of performance is inevitable. The performance expansion of the main network layer1 is slow. No matter how well layer1 develops, it cannot meet the growing user needs at that time. Layer2 expansion will exist for a long time.

Is the existence of layer2 just for expansion?

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Layer 2 scheme

What are the layer2 solutions? I often hear people say roll up, what is it?

It's a long story, there are many solutions: channels, plasma, Sidechain, rollups.

Channels

Also translated as a state channel, the most famous is the payment state channel. Off-chain transactions, on-chain synchronization status. Similar to offline payment and online settlement, it feels a bit like Alipay, but it is not so convenient (of course, most current applications of blockchain are not very convenient). The TPS processing capacity can be very large, because off-chain processing can be very efficient. The problem is that this kind of application is more like an operation agreed by B-end users, and it is difficult to connect with smart contracts to meet the needs of retail investors. Of course, some people say that it is troublesome to set up channels, pledge coins, and monitor channel status. In fact, the core reason is not this. Well-known channel projects, such as Raiden, have a market capitalization that ranks above 500. This technology is similar to the Bitcoin Lightning Network.

Plasma

Suggested by Joseph Poon and Vitalik Buterin. Plasma has the same problem as channels, and cannot expand general-purpose smart contracts. The most famous project is OMG. Vitalik brought it up, but then God V said that rollup is better, so everyone will go after rollup.

Sidechain

Theoretically speaking, the Ethereum side chain, Huobi ecological chain Heco, Binance Smart Chain BSC, and OKChain are all Ethereum side chains. The side chain and the main chain are essentially two chains, and the data and state are not synchronized. Therefore, many big names such as Ethereum fundamentalists and Vitalik are not very supportive of the development of side chains. "My technical code is yours, and yours is still yours." However, the recent rapid development of Heco and BSC has expanded the entire ecology of Ethereum to a certain extent. It can be understood in a simple way that other layer2 solutions can be regarded as pro-sons, and sidechain sidechains are god-sons, and they are very powerful god-sons. People who eat melons are not very concerned about where it is easy to use, where the income is high, and other relatives.

Rollup

Rollup can be translated as "summary". The two words roll up are written separately, which means "roll up".

So what is the rollup of layer2 to summarize? What to roll?

In a word: Summarize multiple transaction information (status) on the side chain to generate a message (hash) and upload it to the Ethereum mainnet. Simplified understanding means that the connection between the side chain and the main chain is opened and already exists. rollup is equivalent to a sidechain without consensus nodes. Some project parties do not have the resources to engage in side chains, and a few servers conduct a rollup to regularly send status information to the main chain to ensure that the information will not be tampered with.

The constantly updated state hash value under the main chain is uploaded to the main chain. The chain cannot independently verify whether the information is true or false. zkrollup can verify this simple information, which is mainly transfer information at present. There are many kinds of rollup schemes for optimistic rollup, such as Optimistic Rollups, ZK Rollups, Arbitrum, StarkEx, etc. Basically, Optimistic Rollup and ZK Rollups are well-known, and other types are mostly improved and debugged versions of these two. Optimistic rollups will run a virtual machine called OVM ((Optimistic Virtual Machine) that can execute the same smart contracts on Ethereum. It actually sounds a bit like the three major public chains (Ethereum side chains), so optimistic rollups and heco, BSC is also closely related to DeFi. Optimism is an important project in the field of optimistic rollups. Loopring, Deversifi, ZKSwap, zkSync, StarkWare and many other projects are doing rollup solutions.

This article is a preliminary understanding of layer2. Searching the Internet keyword "layer2 solution project" can find a large number of projects and interpretation content. It is recommended that you carefully observe and study the top layer2 projects before considering investment matters.