# ERC-20 tokens

Since any arbitrary code may be ran on Ethereum, contracts that create tokens of all types are possible. Bitcoin in its entirety could be a contract on Ethereum as a token, in fact **Wrapped Bitcoin** is a ERC-20 contract and is funded by BTC sent to a contract address allowing Bitcoin to be used in the wider **decentralized finance,** or **DeFi,** ecosystem! This is made possible in-part by Ethereum's ERC-20 standard.\
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The **ERC-20** (**Ethereum Request for Comment #20**) introduces a standard for **fungible tokens** which have a property that makes each token exactly the same (in type and value) as another token of the same contract. For example, an ERC-20 Token acts just like ETH, meaning that 1 token is and will always be equal to all the other tokens of the same type. 

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ERC-20 tokens are commonly referred as just **tokens**.
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Some common examples of ERC-20 tokens are shown here in order of their total market share (Nov 2022):

<figure><img src="https://268056579-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MZJQypB4fk8YIsDKCl_%2Fuploads%2FfeSHNIL56xIO10U7UhKi%2Fimage.png?alt=media&#x26;token=fb00cec9-ae09-4af9-85f3-7a225560c466" alt=""><figcaption></figcaption></figure>

Tokens on Ethereum or any of it's **Layer-2s** have a **contract address** associated with the ERC-20 token that is unique to the contract that created the token. For example the [**DAI stablecoin** ](https://etherscan.io/token/0x6B175474E89094C44Da98b954EedeAC495271d0F)contract has this contract address: [**0x6B175474E89094C44Da98b954EedeAC495271d0F**](https://etherscan.io/token/0x6B175474E89094C44Da98b954EedeAC495271d0F). DAI stablecoin always has this exact contract address on mainnet.