What are the ERC-20 and ERC-721 token standards?

ERC-20 tokens on Ethereum are fungible (like dollars), while ERC-721 tokens are non-fungible (like unique art), enabling diverse applications from cryptocurrencies to NFTs.

Mar 04, 2025 at 08:07 pm

Key Points:

• ERC-20 defines a standard for fungible tokens, meaning each token is interchangeable with another. Think of them like dollars – one dollar is the same as another.
• ERC-721 defines a standard for non-fungible tokens (NFTs), meaning each token is unique and not interchangeable. Think of them like unique pieces of art – each one has its own distinct value and characteristics.
• Both standards operate on the Ethereum blockchain, leveraging its security and decentralized nature.
• Understanding these standards is crucial for developers building on Ethereum and users interacting with various cryptocurrencies and NFTs.

What are ERC-20 and ERC-721 Token Standards?

The Ethereum blockchain, a prominent platform in the cryptocurrency world, supports the creation of various tokens through the use of standardized interfaces known as ERC (Ethereum Request for Comments). Among these, ERC-20 and ERC-721 stand out as two of the most widely adopted standards. They define the fundamental properties and functionalities of tokens, allowing for seamless interoperability between different applications and wallets.

ERC-20: The Standard for Fungible Tokens

ERC-20 is a technical standard that outlines the specifications for creating fungible tokens on the Ethereum network. Fungibility implies that each token is identical to every other token of the same type. Think of it like fiat currency – one dollar bill is equivalent to another. This characteristic is crucial for enabling easy exchange and trading of tokens. ERC-20 tokens are widely used for various purposes, including utility tokens within decentralized applications (dApps), governance tokens that allow holders to participate in decision-making processes, and stablecoins designed to maintain a stable value relative to a fiat currency.

The ERC-20 standard defines several key functions, including methods for transferring tokens, checking balances, and approving spending limits. This standardization ensures that ERC-20 tokens can be readily integrated into various wallets and exchanges. This interoperability is a significant factor in the widespread adoption of the ERC-20 standard. The consistency across different ERC-20 tokens simplifies the development and use of decentralized applications.

ERC-721: The Standard for Non-Fungible Tokens (NFTs)

In contrast to ERC-20, ERC-721 defines the standard for non-fungible tokens (NFTs). NFTs are unique, indivisible tokens that represent ownership of a specific digital or physical asset. Unlike fungible tokens, each NFT is distinct and cannot be interchanged with another. This unique characteristic allows for the representation of various assets, including digital art, collectibles, in-game items, and even real-world assets like real estate.

The ERC-721 standard specifies methods for creating, transferring, and managing NFTs. This includes functions for querying the owner of a specific NFT and retrieving metadata associated with it. The metadata often contains information describing the NFT, such as its image, description, and provenance. This allows for a rich representation of the unique attributes of each NFT. The ability to attach metadata to NFTs is a key factor in their popularity as digital collectibles and other unique assets.

How ERC-20 and ERC-721 Tokens Differ

The fundamental difference between ERC-20 and ERC-721 lies in the fungibility of the tokens. ERC-20 tokens are fungible, meaning one token is identical to another, while ERC-721 tokens are non-fungible, meaning each token is unique. This difference impacts how these tokens are used and their overall purpose within the cryptocurrency ecosystem.

• Fungibility: ERC-20 tokens are fungible, while ERC-721 tokens are non-fungible.
• Use Cases: ERC-20 tokens are used for various applications, including utility, governance, and stablecoins, whereas ERC-721 tokens are used for representing unique digital and physical assets.
• Interchangeability: ERC-20 tokens are interchangeable, while ERC-721 tokens are not.
• Metadata: ERC-20 tokens typically have minimal metadata, while ERC-721 tokens often have extensive metadata associated with them.

Creating ERC-20 and ERC-721 Tokens

Creating tokens that adhere to these standards typically involves using specialized development tools and programming languages like Solidity. The process often requires a basic understanding of blockchain technology and smart contract development.

• Solidity Programming: You'll need to write smart contracts in Solidity, Ethereum's programming language.
• Compilation and Deployment: Compile the smart contract code and deploy it to the Ethereum blockchain using tools like Remix or Truffle.
• Testing: Thoroughly test the deployed smart contract to ensure its functionality and security.
• Verification: Consider verifying your smart contract code on a blockchain explorer to enhance transparency and trust.

Frequently Asked Questions:

Q: Can I create my own ERC-20 or ERC-721 token?

A: Yes, but it requires programming skills and understanding of smart contracts. There are resources and tutorials available to help you learn. However, always prioritize security best practices.

Q: Are ERC-20 and ERC-721 tokens secure?

A: The security of these tokens depends on the implementation of the smart contract. Well-designed and audited contracts are generally secure, but vulnerabilities can exist.

Q: What are the costs involved in creating and deploying ERC-20 and ERC-721 tokens?

A: Costs include gas fees for deploying and interacting with the smart contract on the Ethereum network. These fees vary depending on network congestion.

Q: Where can I learn more about ERC-20 and ERC-721 standards?

A: The Ethereum documentation and various online resources, including tutorials and articles, provide detailed information on these standards.

Q: What are the benefits of using ERC-20 and ERC-721 standards?

A: These standards ensure interoperability and simplify development by providing a common framework for creating and managing tokens. This leads to wider adoption and usability.

Q: Are there any alternatives to ERC-20 and ERC-721?

A: Yes, other blockchain platforms have their own token standards. However, ERC-20 and ERC-721 remain dominant on the Ethereum network.