Ethereum's ERC-20 Tokens – All You Need to Know

Overview

What is ERC-20: ERC-20 represents one of the most widely-adopted standards for smart contracts on the Ethereum platform. All ERC-20 tokens are issued according to the same technical standard, which enables them to operate seamlessly on the Ethereum blockchain. This standardization has been crucial in fostering interoperability across the entire Ethereum ecosystem.

According to Etherscan, there are over 350,000 ERC-20 token contracts deployed on the Ethereum blockchain. These tokens serve various purposes, including stablecoins that maintain price stability, DeFi tokens that power decentralized finance applications, and utility tokens that provide specific functionalities within their respective projects.

Ethereum & ERC-20 Tokens

When Ethereum launched in 2015, it marked the beginning of a transformative era for blockchain technology. Previously, blockchain's utility was predominantly limited to cryptocurrencies like Bitcoin, which primarily functioned as digital currencies. Ethereum revolutionized this landscape by introducing the first-ever smart contract platform, quickly establishing itself as the second-largest cryptocurrency by market capitalization and attracting a substantial community of supporters and investors.

The years following Ethereum's launch witnessed an explosive growth of new blockchain projects, with the ERC-20 token standard serving as the foundation for this expansion. The standardization brought by ERC-20 has been instrumental in creating a unified ecosystem where tokens can interact seamlessly with various platforms, wallets, and decentralized applications.

All ERC-20 tokens are issued according to the same technical standard, which allows them to operate on the Ethereum blockchain with consistent behavior and predictable functionality. In this comprehensive guide, we'll explore the fundamental concepts of the ERC-20 token standard and examine the rules governing how new ERC-20 tokens are issued. Additionally, we'll investigate the diverse use cases for ERC-20 tokens that are currently operational in the cryptocurrency space.

What Are ERC-20 Tokens and Smart Contracts?

Like Bitcoin, Ethereum operates as a blockchain consisting of blocks that contain transactions, maintaining a complete historical record dating back to the genesis block. However, Ethereum incorporates an additional layer known as the Ethereum Virtual Machine, or EVM. The EVM is the revolutionary component that enables developers to program and deploy smart contracts on the Ethereum platform.

A smart contract is essentially a piece of code written in Solidity, Ethereum's native programming language, that operates on conditional logic following an "if-this-then-that" structure. The concept can be understood through a simple analogy: it functions similarly to a vending machine. When you insert a coin into a vending machine, the machine automatically dispenses a product—such as a can of soda or a candy bar—in return. Smart contracts are programmed to execute transactions in a comparable automated manner, executing predefined actions when specific conditions are met.

ERC-20 represents one of the most extensively utilized standards for smart contracts on the Ethereum platform. The fact that nearly all Ethereum tokens are issued according to this same standard provides substantial benefits for users within the Ethereum ecosystem. This standardization ensures that ERC-20 tokens are interoperable with one another and compatible with any ERC-20 supported contract, exchange, marketplace, or wallet.

This capability for seamless integration has created a positive reinforcement cycle for Ethereum's growth. The existing robust ecosystem continues to attract more developers and users who want to participate, further strengthening the network effect and expanding the platform's utility and reach.

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

The ERC-20 token standard is relatively straightforward in its design, comprising nine distinct rules for issuing tokens. Six of these rules are mandatory and must be implemented in all instances to ensure compliance with the standard. Three rules are optional, although at least two of these optional rules are generally implemented by token creators to enhance usability and recognition.

Optional Rules

The three optional rules provide flexibility for token customization:

1. Token Name – For example, Maker. Despite being classified as optional, this rule is almost universally implemented because token creators want users to easily identify and recognize their tokens in the marketplace.

2. Token Ticker – For example, MKR. This is also nearly always used because cryptocurrency exchanges list trading pairs using ticker symbols, making this essential for practical trading purposes.

3. Decimal – Each ERC-20 token can be denominated in fractional units of up to one-eighteenth of a whole token, allowing for precise value representation and microtransactions.

Mandatory Rules

Mandatory rules are categorized as either functions or events, each serving specific purposes in token operation. The first two functions are read-only operations that don't modify the state of the contract. They define core features of the token and, when queried, return predefined information about the token's current state.

• TotalSupply – This function returns the total number of tokens that have been issued, providing transparency about the token's supply.

• BalanceOf – This function answers queries regarding how many tokens any given address is currently holding, enabling users to check their token balances.

Another two mandatory components are commonly-used events that are familiar to all cryptocurrency users and essential for token transfers:

• Approve – This event approves the movement of tokens in a transfer, providing authorization for token transfers to occur.

• Transfer – Once approved, this function instructs the smart contract to move a defined value of tokens from a sender address to a recipient address, executing the actual token transfer.

Finally, there are two additional mandatory rules that may not be actively implemented in all use cases, but they must be included in the code to qualify the token as compliant with the ERC-20 standard:

• Allowance – ERC-20 allows an address to be programmed with a spendable allocation of tokens that can be sent by the smart contract without requiring additional approval for each transaction. It's effectively a pre-approval mechanism to spend an allowance. This function is defined as zero by default, but when queried, it will return the number of tokens remaining in the allowance.

• TransferFrom – This function allows a token to be programmed for automatic payments, initiating the Transfer event to move tokens from an Allowance without requiring manual intervention for each transaction.

Providing that any given Ethereum token implementation adheres to these rules, the token is considered to be using the ERC-20 token standard. Token issuers have the flexibility to implement additional programming rules that govern how their tokens behave beyond these basic requirements. For instance, if a project founder is conducting a crowdfunding campaign using tokens, they can program a smart contract to automatically dispense ERC-20 tokens to investors. When an investor sends a specified amount of ETH from their wallet and deposits it into the smart contract, the contract will automatically return the purchased tokens to the investor's wallet, creating a seamless and trustless transaction process.

Notable Projects Using the ERC-20 Token Standard

According to Etherscan, there are over 350,000 ERC-20 token contracts deployed on the Ethereum blockchain. It's reasonable to acknowledge that at least some of these represent inactive or abandoned projects. Many blockchain projects choose to issue the first instance of their token on Ethereum because the process is quick, cost-effective, and provides immediate access to a large ecosystem. EOS serves as one prominent example of a project that initially started with ERC-20 tokens before eventually migrating to issue native tokens on its own independent mainnet.

However, numerous well-known and actively utilized projects in the cryptocurrency space continue to operate as ERC-20 tokens and are likely to maintain this standard for the foreseeable future. These projects have found that the benefits of remaining within the Ethereum ecosystem—including access to DeFi protocols, established wallets, and major exchanges—outweigh the potential advantages of launching independent blockchains.

Here are some of the main project types and categories that extensively utilize the ERC-20 standard:

Stablecoins

All of the largest stablecoins are issued as ERC-20 tokens, primarily due to their seamless interoperability with DeFi protocols and other Ethereum-based applications. For instance, Tether's USDT, Circle's USDC, and stablecoins from major exchanges are all available as ERC-20 tokens. These stablecoins have become fundamental infrastructure for the cryptocurrency ecosystem, facilitating trading, lending, and various DeFi operations.

Some stablecoins are issued on multiple blockchain networks to overcome challenges associated with the Ethereum platform, such as network congestion and elevated transaction fees during periods of high demand. For example, USDT is available on Tron, Omni, and EOS networks as well, providing users with alternatives when Ethereum gas fees become prohibitively expensive.

Maker's DAI stands out as an ERC-20 token and represents the largest crypto-backed stablecoin in the ecosystem. Unlike centralized stablecoins backed by fiat currency reserves, DAI maintains its peg through overcollateralized cryptocurrency deposits, making it a cornerstone of decentralized finance.

DeFi Tokens

Some of the largest ERC-20 tokens by market capitalization and user adoption in recent years are DeFi tokens. These tokens offer various features, including yield generation opportunities, governance rights that allow holders to vote on protocol decisions, and utility within their respective platforms. DeFi tokens gained significant popularity in 2020 when Compound launched its COMP token, introducing the concept of "yield farming" to the broader cryptocurrency community.

Since that pivotal moment, other projects including Uniswap's UNI, Sushiswap's SUSHI, and Yearn's YFI have experienced similar success, building substantial communities and achieving significant market valuations. These tokens have demonstrated the power of decentralized governance and the potential for token holders to participate directly in protocol development and decision-making processes.

Utility Tokens

Numerous instances of ERC-20 tokens offer specific utility within particular projects or ecosystems. Utility tokens encompass a wide variety of use cases developed by blockchain entrepreneurs to solve real-world problems or enhance user experiences. For example, Basic Attention Token (BAT) serves as the native token used by participants in the Brave browser advertising ecosystem, creating a new model for digital advertising that rewards users for their attention.

Other utility tokens provide access to platform features, enable payment for services, or grant holders special privileges within their respective ecosystems. This category demonstrates the versatility of the ERC-20 standard in supporting diverse business models and use cases.

Finally, it's worth noting that ERC-20 tokens are also supported on several other blockchain platforms beyond Ethereum itself. For example, Matic Network (now Polygon) is a Layer 2 scaling solution developed to overcome Ethereum's scalability limitations. It utilizes the Ethereum Virtual Machine, enabling it to interoperate seamlessly with ERC-20 tokens. This compatibility means that the ERC-20 ecosystem extends beyond Ethereum's base layer, encompassing various scaling solutions and sidechains that maintain EVM compatibility.

Conclusion

ERC-20 tokens are not necessarily perfect solutions for every use case, and all smart contracts are only as reliable as the underlying code on which they're based. Security vulnerabilities, coding errors, or design flaws can potentially compromise token functionality or user funds. However, ERC-20 tokens are generally straightforward to issue, highly versatile in their applications, and exceptionally well-supported within the broader cryptocurrency space.

The standard has proven its resilience and utility over several years of operation, supporting hundreds of thousands of tokens and facilitating trillions of dollars in transaction volume. The extensive developer tooling, wallet support, and exchange integration available for ERC-20 tokens create a robust infrastructure that continues to attract new projects.

For these compelling reasons, it's reasonable to assume that ERC-20 will remain the most popular and widely-adopted token standard for the foreseeable future. As Ethereum continues to evolve with upgrades and scaling solutions, the ERC-20 standard will likely maintain its position as the foundation for tokenization in the blockchain ecosystem.

FAQ

What is an ERC-20 token and what is its purpose?

ERC-20 is a standardized token format on Ethereum enabling interchangeable digital assets. It serves as the framework for stablecoins, utility tokens, and security tokens, allowing seamless integration with wallets and DApps while maintaining predefined supply limits.

What is the difference between ERC-20 tokens and Bitcoin?

ERC-20 tokens are standards on the Ethereum blockchain, while Bitcoin operates on its own independent blockchain. ERC-20 tokens enable smart contracts and DeFi applications, whereas Bitcoin serves as digital currency and store of value.

How to create and issue your own ERC-20 token on Ethereum?

Install MetaMask, obtain test ETH on a testnet, write a Solidity smart contract using Remix IDE, compile and deploy it to the blockchain, then add the token address to your wallet.

What are the security risks of ERC-20 tokens? How do I protect my token assets?

Main risks include smart contract vulnerabilities and wallet hacks. Protect yourself by using hardware wallets, enabling two-factor authentication, and auditing token contract code before engagement.

What is the difference between ERC-20 and other Ethereum token standards like ERC-721 and ERC-1155?

ERC-20 is for fungible tokens, ERC-721 for non-fungible tokens, and ERC-1155 combines both, supporting fungible and non-fungible tokens simultaneously.

How to buy, store and trade ERC-20 tokens?

Use Web3 wallet to connect to decentralized exchanges for purchasing ERC-20 tokens. Store them securely in your Web3 wallet with backup seed phrase and two-factor authentication enabled. Trade tokens directly through supported DEX platforms as needed.

What is the smart contract principle of ERC-20 tokens?

ERC-20 smart contracts define token behavior and attributes, including total supply and transfer functions. These contracts run on the Ethereum blockchain, ensuring standardized token transactions and interoperability across the network.

Which well-known cryptocurrency projects use the ERC-20 standard?

Popular ERC-20 tokens include Tether (USDT), Chainlink (LINK), Uniswap (UNI), and Aave (AAVE). These projects leverage ERC-20 for fungible token functionality on Ethereum, supporting DeFi applications and decentralized exchanges.