Everything You Need to Know About Ethereum's ERC-20 Tokens

Ethereum and ERC-20 Tokens

When Ethereum launched in 2015, it marked the beginning of a new era for blockchain technology. Previously, the utility of blockchain was mostly limited to cryptocurrencies like Bitcoin. However, Ethereum, as the first smart contract platform, quickly became the second-largest and most popular cryptocurrency, attracting numerous supporters and investors eager to purchase Ether. In the years following its launch, there was an explosion of new projects powered by ERC-20 tokens.

All ERC-20 tokens adhere to the same standards that enable them to operate on the Ethereum blockchain. This standardization has created a unified ecosystem where tokens can seamlessly interact with each other and with various Ethereum-based applications. In this comprehensive guide, we will explore all the essential information about the ERC-20 token standard and examine the rules governing how new ERC-20 tokens are created. Additionally, we will look at numerous use cases of ERC-20 tokens currently in operation, demonstrating their versatility and widespread adoption in the blockchain space.

What Are ERC-20 Tokens and Smart Contracts?

Like Bitcoin, Ethereum is a blockchain consisting of transactions that encompass its entire history since the genesis block. However, Ethereum has an additional layer known as the Ethereum Virtual Machine (EVM). The EVM is the layer that allows anyone to program smart contracts on the Ethereum platform, enabling developers to create decentralized applications with various functionalities.

A smart contract is a piece of code written in Solidity, Ethereum's programming language, that operates on "if this, then that" logic. It works similarly to a vending machine: when you insert coins into a vending machine, you automatically receive a box of soda or candy in return. A smart contract is programmed in the same way, executing predetermined actions when specific conditions are met. This automation eliminates the need for intermediaries and ensures trustless execution of agreements.

ERC-20 is one of the most widely used standards for smart contracts on the Ethereum platform. The fact that nearly all Ethereum tokens are organized under the same standard provides significant benefits for users of the Ethereum ecosystem. This standardization means that ERC-20 tokens can work with each other and with any ERC-20-supported contract, exchange, marketplace, or wallet. The interoperability extends across the entire ecosystem, making it easier for developers to build compatible applications and for users to manage their digital assets.

This integration capability acts as a positive reinforcement loop for Ethereum, attracting more developers and users who want to participate in the existing ecosystem. The network effects created by this standardization have been instrumental in Ethereum's growth and dominance in the smart contract space.

What Are the Rules Governing the ERC-20 Token Standard?

The ERC-20 token standard contains nine relatively simple rules for issuing tokens. Six of these are mandatory and must be implemented in every case, while three are optional, though at least two of them are generally used in practice. This structured approach ensures consistency while allowing for flexibility in token design.

Optional Rules

The three optional rules are as follows:

1. Token Name – For example, Maker. Although optional, this is almost always used because token owners want users to be able to identify their tokens easily. A descriptive name helps with brand recognition and user adoption.

2. Token Symbol – For example, MKR. Most of the time, exchanges list token pairs using these symbols, making them essential for trading and market identification. These symbols typically consist of three to five characters.

3. Decimals – Each ERC-20 token can be defined in fractional units up to one-eighteenth. This divisibility allows for micro-transactions and precise value transfers, similar to how Bitcoin can be divided into satoshis.

Mandatory Rules

The mandatory rules are categorized as functions or events. The first two functions do not change the state of the contract but rather define some basic properties of the token and return predefined information when queried.

• Total Supply – The total number of tokens issued. This function provides transparency about the token's scarcity and helps users understand the token economics.

• BalanceOf – Answers a query about how many tokens any address holds. This function is essential for wallets and exchanges to display user balances accurately.

The other two are commonly used events that all cryptocurrency users are familiar with:

• Approve – Approves the movement of tokens in a transfer. This function allows token holders to authorize third parties to spend tokens on their behalf, which is crucial for decentralized exchanges and other DeFi applications.

• Transfer – After approval, this function instructs the contract to move a defined value of tokens from the sender's address to the recipient's address. This is the core functionality that enables token transactions.

Finally, there are two more that cannot be implemented, but they must be included to qualify the token as compliant with the ERC-20 standard:

• Allowance – ERC-20 allows an address to be programmed with a spendable token allocation that can be sent by the smart contract without any approval. Allowance is an effective pre-approval for spending. This function is defined as zero by default but returns the number of tokens remaining in the allowance when queried. This mechanism is particularly useful for automated payments and subscription services.

• TransferFrom – Allows a token to be programmed for automatic payments, initiating the Transfer event to move tokens from an Allowance. This function enables complex financial operations and automated workflows within decentralized applications.

Therefore, any Ethereum token implementation can use the ERC-20 token creation standard provided it complies with these rules. Token-issuing organizations can establish additional programming rules that govern how tokens behave. For example, if a project founder is crowdfunding using tokens, they can program a smart contract to automatically distribute ERC-20 tokens. When an investor sends a certain amount of ETH from their wallet and deposits it into the smart contract, the purchased tokens will be returned to the investor's wallet automatically, creating a seamless investment experience.

Major Projects Using the ERC-20 Token Creation Standard

According to Etherscan, there are over 350,000 ERC-20 token contracts on the Ethereum blockchain. It would be fair to say that at least some of these will be dead coins, representing failed or abandoned projects. Many projects prefer to issue the first instance of their tokens on Ethereum because it is fast and easy, leveraging the existing infrastructure and user base. EOS is an example of a project that started this way before issuing EOS tokens on its own mainnet.

However, some of the best-known and most-used projects in cryptocurrency still operate as ERC-20 tokens and are likely to continue to do so in the future. The Ethereum ecosystem has proven robust enough to support projects of all sizes and purposes. Below are some major project types and categories that demonstrate the versatility of the ERC-20 standard.

Stablecoins

All of the largest stablecoins are issued as ERC-20 tokens due to their interoperability with DeFi and other Ethereum applications. For example, Tether's USDT, Circle's USDC, and a major stablecoin BUSD are all available as ERC-20 tokens. These stablecoins play a crucial role in the cryptocurrency ecosystem by providing price stability and serving as a bridge between traditional finance and decentralized applications.

To overcome issues with the Ethereum platform such as congestion and high transaction fees, some stablecoins are issued on multiple networks. For example, the USDT stablecoin is also available on Tron, Omni, and EOS, allowing users to choose the most cost-effective network for their transactions. This multi-chain approach demonstrates how successful token standards can extend beyond their original platform.

Maker's DAI is an ERC-20 token and the largest crypto-backed stablecoin, representing a significant innovation in decentralized finance. Unlike centralized stablecoins, DAI maintains its peg through algorithmic mechanisms and over-collateralization, showcasing the power of smart contracts.

DeFi Tokens

Currently, some of the largest ERC-20 tokens by market value and popularity are DeFi tokens. DeFi tokens, which gained popularity in the summer of 2020 when Compound launched its COMP token, offer different features including yield generation and governance rights. This period, often referred to as "DeFi Summer," marked a turning point in the adoption of decentralized financial services.

Since then, others have achieved similar success, including Uniswap's UNI, Sushiswap's SUSHI, and Yearn's YFI. These tokens not only serve as governance mechanisms but also provide economic incentives for liquidity providers and active participants in their respective protocols. The success of these projects has demonstrated that ERC-20 tokens can power complex financial systems without traditional intermediaries.

Utility Tokens

Some examples of ERC-20 tokens provide utility within a specific project. Utility tokens have a wide variety of use cases developed by blockchain entrepreneurs, serving purposes ranging from access rights to ecosystem incentives. For example, Basic Attention Token is a token used by participants in the Brave browser advertising ecosystem, rewarding users for their attention and enabling a more equitable digital advertising model.

Utility tokens represent one of the most innovative applications of blockchain technology, enabling new business models and economic systems. They can grant access to services, represent voting power in decentralized organizations, or serve as rewards in gamified ecosystems. The flexibility of the ERC-20 standard makes it ideal for these diverse applications.

Finally, it is worth noting that ERC-20 tokens are also supported on some other platforms, extending their reach beyond Ethereum. For example, Polygon Network is a layer-two platform developed to overcome Ethereum scalability issues. It uses the Ethereum Virtual Machine and thus can work with ERC-20 tokens. This means that the ERC-20 ecosystem is even larger than Ethereum itself, with various scaling solutions and side chains supporting these tokens.

Conclusion

ERC-20 tokens may not be perfect, and all smart contracts are only as good as the code they are based on. Security vulnerabilities and implementation errors can lead to significant losses, highlighting the importance of thorough auditing and best practices in smart contract development. However, issuing ERC-20 tokens is generally simple, versatile, and well-supported in the cryptocurrency space.

The standardization provided by ERC-20 has lowered barriers to entry for new projects while ensuring compatibility across the ecosystem. This balance between accessibility and functionality has been key to Ethereum's success as a platform for innovation. Therefore, it would be reasonable to assume that ERC-20 will remain the most popular token standard for some time to come.

The network effects created by widespread adoption, combined with ongoing improvements to the Ethereum platform, suggest that ERC-20 tokens will continue to play a central role in the evolution of decentralized finance and blockchain applications. As the technology matures and new use cases emerge, the ERC-20 standard will likely adapt and evolve while maintaining its core principles of interoperability and standardization.

FAQ

What is the ERC-20 token standard and what role does it play in the Ethereum ecosystem?

ERC-20 is Ethereum's fungible token standard defining rules for interchangeable tokens. It forms the foundation of DeFi, enabling seamless asset trading, lending, and financial operations across decentralized applications and protocols.

How to create your own ERC-20 token? What technical foundation and tools are needed?

Write a smart contract in Solidity following the ERC-20 standard, deploy it on Ethereum blockchain using tools like Remix or Hardhat. Basic blockchain and smart contract knowledge is required for successful token creation.

What is the difference between ERC-20 tokens and other token standards such as ERC-721 and ERC-1155?

ERC-20 is a fungible token standard for interchangeable assets like currencies. ERC-721 is a non-fungible token standard for unique items like NFTs. ERC-1155 combines both, supporting fungible and non-fungible tokens in a single contract.

What security risks should I be aware of when using and trading ERC-20 tokens?

Key risks include gas fee volatility, smart contract vulnerabilities, fake token scams, phishing attacks, and wallet security breaches. Always verify contract addresses, use secure wallets, and research projects thoroughly before trading.

Why is contract auditing and security certification important for ERC-20 tokens?

Contract audits and security certifications identify vulnerabilities and reduce attack risks. They ensure code reliability through rigorous testing, building user trust and protecting funds from exploits.

How to add and manage ERC-20 tokens in a wallet?

Import the token contract address into your wallet to add ERC-20 tokens. Use Ethereum-compatible wallets to view balances and manage holdings. Confirm transactions on the Ethereum network to transfer tokens securely.

How are ERC-20 token Gas fees calculated? How to optimize transaction costs?

ERC-20 Gas fees = (Base Fee + Priority Fee) × Gas Limit. Optimize by adjusting Gas Limit, choosing off-peak times, and using batch transactions to reduce overall transaction volume.

Which notable projects use the ERC-20 standard? What are their characteristics?

Major ERC-20 projects include Uniswap, Aave, and USDC. These tokens are fungible and interchangeable, serving as foundational assets for DeFi applications including decentralized exchanges, lending protocols, and liquidity mining.