• 
  

• Solana : pos with poh (history)

• avalanche

• 侧链: polygon

cryptocurrencies vs tokens 

• cryptocurrencies are the native asset of a blockchain — like BTC or ETH — whereas tokens are created as part of a platform that is built on an existing blockchain, like the many ERC-20 tokens that make up the Ethereum ecosystem. 

  • For instance, the Ethereum blockchain’s native token is ether (ETH). While ether is the cryptocurrency native to the Ethereum blockchain,

  • Crypto tokens built using Ethereum include DAI, LINK, COMP, and CryptoKitties, among others. These tokens can serve a multitude of functions on the platforms for which they are built, including participating in decentralized finance (DeFi) mechanisms, accessing platform-specific services, and even playing games. 

• While tokens often share deep compatibility with the cryptocurrencies of that network, they are a wholly different digital asset class . 

A crypto wallet has three main components:

• Public Key: This links to an address where you can send and receive transactions. 

• Private Key: Must be kept secret and undisclosed. This is used for signing new transactions and enables access to funds.

• Seed Phrase: Used to generate multiple private keys. Act as a root key, giving access to the rest of the keys and addresses in a user’s wallet. This can also create new private keys.

Take note: Cryptocurrency like Bitcoins are not stored in wallets. Instead Private/public keys are stored in wallets.

                            Bitcoins only exist within the public Bitcoin blockchain

In Web3, several types of wallets exist within the space 

• • Hot Wallets: generally referred to as software wallets because they are hosted on devices that have access to the internet and cryptocurrency network. They are more convenient than other types of wallets due to their ability to store, send, receive, and view tokens. Hot wallets are considered the highest in utility when it comes to Web3 wallets.  Since hot wallets are connected to the web, they’re open to more hacks compared to cold wallets. 

  • Desktop Wallets: simply are downloaded as an application to our laptop or desktop. That means it is executed locally in the machine. They are considered the safest type of hot wallets available.

  • Web Wallets: Web wallets are installed on someone else’s computer or server. It allows people to interact via a browser interface. Therefore, it isn’t necessary to download or install anything on a device. It consists of the exact same features as desktop wallets, using the same blockchains and block explorer to search blocks and transactions. 

  • Mobile Wallets: These are very similar and work much like desktop wallets, except are designed specifically as mobile apps for smartphones. This gives users access convenient access to their funds at the palm of their hands. Mobile wallets tend to be more primitive compared to desktop apps due to limited space and the use case for simplicity.

  • Cold Wallets: Cold wallets tend to be a safer alternative to store cryptocurrencies because of no connection to the internet. This is because there is a physical medium to store the keys offline. This method makes cold wallets increasingly resistant to hackers, which is known as cold storage. This is specifically useful for long-term investors.

  • Hardware Wallets: Hardware wallets are physical electronic devices (often resembling a USB device) that use a Random number generator (RNG) to generate public and private keys. This is considered one of the safest alternatives because of its ability to hold public and private keys in the device without any connection to the internet. Therefore, access to your cryptocurrencies will be offline. Using hardware wallets for cold storage enables users to have more security and prevents hackers from accessing their funds. As such, hardware wallets are most suitable for long-term investing and storage because they tend to be less accessible. Its main use case is for ensuring a high amount of security for large sums of money not allocated for constant usage.

  • Paper Wallets: A paper wallet is a piece of paper consisting of which a blockchain address and private key are physically printed out. These keys are printed out as QR codes. People can send funds by scanning QR codes. Usage for paper wallets isn’t commonly used today and is often discouraged due to its fundamental flaws. One of these flaws is that paper wallets can’t send partial funds and can only send the entire balance all at once.

区块链软件技术架构图 区块链技术框架图

公链、私链、联盟链 、侧链

以太坊：包括编程语言 solidity

Testnet

目前，以太坊网络常用的测试网有下面两个：

Goerli：权益证明测试网，它有望得到长期维护，作为面向应用程序开发者的稳定测试网。

Sepolia：权益证明测试网，尽管 Sepolia 仍在运行，但据说未来可能会停止维护。

由于 Goerli 测试网现阶段依然还是以太坊主流的测试网，所以目前很多的水龙头都是基于 Goerli 测试网的。但大多数水龙头不是随便就可以直接领取的，而是需要社交身份验证（例如在社交网站发帖确认或登录确认是你本人）或让你排队等待通过水龙头的测试网Token。而测试网Token是一种测试货币，允许用户在主网上线之前测试相关的以太坊应用程序。

这里额外有一点需要提醒的是，测试网代币是可以用来代替Goerli等测试网上的主网ETH的。如果你从龙头那里得到了免费的Goerli ETH，并想把它换成真正的可以交易的以太坊（ETH）代币，那么你可以通过Testnet Bridge来实现（即LayerZero Testnet Bridge）。目前，Goerli ETH 的和ETH转换率是1:0.0000856，这也意味着，每当你免费领到1个Goerli ETH时，你可以换到0.000856个ETH。因为这也是羊毛，所以被各种机器人薅的厉害，导致现在普通用户也很难领取到免费的Goerli ETH了！