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  • We all hear about ERC20 tokens but what are those tokens and most importantly: what are

  • they not?

  • To start with, let's quickly go over some basics: ERC20 tokens exist on the Ethereum

  • platform and that in itself consists out of a blockchain that is capable of storing transactions

  • and a virtual machine that is capable of running smart contracts.

  • It's important to understand that tokens live on the Ethereum blockchain.

  • They benefit from its technology.

  • They aren't independent and rely on Ethereum's blockchain and platform.

  • The native currency on the Ethereum network is Ether.

  • But besides Ether, it can also support other tokens and these can work like currencies

  • but they can also represent shares of a company, loyalty points, gold certificates and so on

  • But we're running ahead a bit.

  • Let's first look at how tokens come into existence.

  • A token can be created by a smart contract.

  • This contract is not only responsible for creating tokens but also for managing transactions

  • of the token and keeping track of each tokens holder's balance.

  • To get some tokens you have to send some Ether to the smart contract, which will then give

  • you a certain amount of tokens in return.

  • So when you want to create your own token, you write a smart contract that can create

  • tokens, transfer them and keep track of people's balances.

  • That sounds pretty easy but it's also quite risky.

  • For starters, once a smart contract is deployed it cannot be changed anymore, so if you made

  • an error you can't fix it.

  • That could be quite catastrophic.

  • Imagine a bug inside your contract's code that causes people to loose their tokens or

  • a bug that would allow others to steal tokens.

  • And then there is the problem of interoperability.

  • Each token contract can be completely different from the other.

  • So if you want your token to be available on an exchange, the exchange has to write

  • custom code so they can talk to your contract and allow people to trade.

  • Same thing goes for wallet providers.

  • Supporting hundreds of tokens would be very complex and time consuming.

  • So instead, the community proposed a standard called ERC20.

  • ERC stands forEthereum Request for Commentsand 20 is just the number they assigned to

  • a proposal that would create some structure in the wild west of tokens.

  • ERC20 is a guideline or standard for when you want to create your own token.

  • It defines 6 mandatory functions that your smart contract should implement and 3 optional

  • ones.

  • To start with you can optionally give your token a name, a symbol and you can control

  • how dividable your token is by specifying how many decimals it supports.

  • The mandatory functions are a bit more complex: for starters you have to create a method that

  • defines the total supply of your token.

  • When this limit is reached, the smart contract will refuse to create new tokens.

  • Next up is the `balanceOf` method which has to return how many tokens a given address

  • has.

  • Then there are two transfer methods: `transfer` which takes a certain amount of tokens from

  • the total supply and gives them to a user and `transferFrom` which can be used to transfer

  • tokens between any two users who have them.

  • Finally there is the `approve` and `allowance` methods.

  • `Approve` verifies that your contract can give a certain amount of tokens to a user,

  • taking into account the total supply.

  • The `allowance` method is almost the same except that it checks if one user has a high

  • enough balance to send a certain amount of tokens to someone else.

  • If you know something about object oriented programming then you can compare ERC20 to

  • an interface.

  • If you want your token to be an ERC20 token, you have to implement the ERC20 interface

  • and that forces you to implement these 6 methods.

  • Before there was the ERC20 standard, everyone who wanted to create a token had to reinvent

  • the wheel.

  • And that meant that each token contract was slightly different and that exchanges and

  • wallets had to write custom code to support your token.

  • With ERC20 however exchanges and wallet providers only have to implement this code once.

  • That's why exchanges can add new tokens so quickly and why wallets like MyEtherWallet

  • have support for all ERC20 tokens, without having to be updated.

  • So how easy would be it be to create your own token?

  • Well there is a website called TokenFactory that does it all for you.

  • You just enter what the total supply of your token should be, how you want to call it,

  • how many decimals it should support and what symbol it should have.

  • After entering all this, the website creates a token contract for you and adds it to the

  • Ethereum blockchain.

  • It's super easy and almost effortless.

  • So effortless in fact that the website Etherscan has a list of 36,000 known ERC20 tokens and

  • it's estimated that in 2017 over 4 billion dollars was raised by selling tokens in an

  • ICO.

  • However these tokens we're not always clean.

  • Some were really overhyped and many people got scammed into purchase tokens that where

  • essentially worthless.

  • But now we're getting a bit distracted.

  • ERC20 is a great standard that has propelled the use of tokens.

  • But ERC20 itself is not perfect.

  • It's only a guideline and people are free to implement the required functions however

  • they like.

  • That has lead to some interesting problems.

  • For instance: to buy some tokens you have to send some ether to the token contract.

  • But some people tried sending other ERC20 tokens instead.

  • If the contract was not designed with this in mind, it will result in your tokens being

  • lost.

  • In fact, it was estimated that by December 2017 well over 3 million dollars have been

  • lost because of this flaw.

  • So to solve this, the community is already working on extending the ERC20 standard with

  • the ERC223 standard.

  • This warns token creators about these risks and offers some workarounds.

  • Let me know what you think about ERC20 tokens in the comments below or send a tweet to @Savjee.

  • Thank you very much for watching and don't forget to subscribe so I see you in the next

  • video!

We all hear about ERC20 tokens but what are those tokens and most importantly: what are

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ERC20トークン - 簡単に説明します。 (ERC20 tokens - Simply Explained)

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    Yi-Cheng Guo に公開 2021 年 01 月 14 日
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