Token Standards: ERC-20, ERC-721, and Why They Matter

Standards are the invisible infrastructure that makes an entire ecosystem possible.

Think about electrical outlets for a moment. When you walk into a hotel room in Chicago or Seattle or Miami, you don't think twice about plugging in your phone charger. You know it'll fit. You know it'll work. That's not an accident. That's a standard—specifically, the NEMA 5-15 standard for electrical outlets in North America. Without it, every appliance manufacturer would build different plugs, every building would wire different sockets, and you'd need an adapter collection just to live your life. Standards eliminate friction. They create interoperability. They make complexity invisible.

Token standards on Ethereum work the same way. They're technical specifications that tell developers, wallets, exchanges, and smart contracts how to interact with tokens in predictable ways. Without them, the entire ecosystem would collapse into chaos.

Let's start with ERC-20, because it's the foundation of everything. ERC stands for Ethereum Request for Comment, which is just the formal process for proposing standards. The number twenty? That's simply the proposal number. Nothing mystical about it. Fabian Vogelsteller and Vitalik Buterin proposed ERC-20 back in 2015, and it was formally accepted in 2017.

What ERC-20 does is define how fungible tokens should behave. Fungible means interchangeable. One dollar bill works exactly like another dollar bill. One share of Apple stock is identical to any other share of Apple stock. One bitcoin equals one bitcoin. ERC-20 tokens follow the same principle. If you have one unit of an ERC-20 token called, say, LINK, it's identical to anyone else's LINK token. They're perfectly substitutable.

The genius of ERC-20 isn't complicated. It just specifies six mandatory functions that every compliant token must implement. Things like totalSupply, which tells you how many tokens exist. BalanceOf, which tells you how many tokens a specific address holds. Transfer, which lets you send tokens from one address to another. There are a few more, but you get the idea. By agreeing to implement these functions, token creators ensure that their token will work with every wallet, every exchange, every decentralized application that supports ERC-20.

Think about what that enables. MetaMask doesn't need to know anything special about Chainlink or Uniswap or any of the thousands of ERC-20 tokens. It just needs to know the standard. Coinbase can list a new ERC-20 token without rebuilding their entire infrastructure. A decentralized exchange can allow trading pairs for tokens that didn't even exist when the exchange was built. That's the power of interoperability.

Now, this might sound dry and technical, but consider the alternative. In the early days of cryptocurrency, before standards, every token was essentially custom-built. If you wanted your token to work with a wallet or exchange, you had to convince those platforms to write custom code specifically for your token. It was slow, expensive, and it didn't scale. ERC-20 changed that overnight. Suddenly, anyone could create a token that worked everywhere. That's why we saw the ICO boom in 2017. Whether you think that was good or bad, it was only possible because the standard removed the technical barriers.

But fungible tokens don't solve every problem. Sometimes you need to represent something unique. A piece of art. A specific concert ticket. A deed to a particular house. These things aren't interchangeable. Your ticket to row fifteen, seat eight isn't the same as someone else's ticket to row thirty, seat twelve, even though they're both tickets to the same concert.

That's where ERC-721 comes in. This is the non-fungible token standard, proposed by William Entriken, Dieter Shirley, Jacob Evans, and Nastassia Sachs in 2017 and finalized in 2018. The name might sound like technical jargon, but non-fungible just means unique and not interchangeable.

ERC-721 works similarly to ERC-20 in that it defines mandatory functions that compliant tokens must implement. But the key difference is that each token has a unique identifier. Instead of just tracking how many tokens an address owns, ERC-721 tracks which specific tokens an address owns. Token number 5,823 is distinct from token number 9,047. They might both be part of the same collection, but they're not identical.

The most famous example is probably CryptoPunks, though technically CryptoPunks predates the ERC-721 standard and doesn't fully conform to it. But something like Bored Ape Yacht Club does. Each ape is a distinct NFT with its own token ID. When you buy one, you're not getting a fungible unit of "ape." You're getting that specific ape with that specific combination of traits.

Now, you might be thinking, what's the practical value here beyond profile pictures and digital collectibles? Fair question. The answer is that uniqueness matters for lots of things. Domain names, where each .eth address is distinct. Digital identity credentials, where your proof of attendance at a specific event is unique to you. Gaming items, where your legendary sword with specific attributes isn't the same as someone else's legendary sword. Real estate titles, where the deed to 742 Evergreen Terrace isn't the same as the deed to 123 Main Street.

The standard doesn't create the value. It just makes the value portable and interoperable. Your ERC-721 token works with OpenSea, Rarible, any compatible marketplace, any compatible wallet. The standard creates the infrastructure for markets to exist.

There are other standards too. ERC-1155, for instance, is a multi-token standard that lets you combine fungible and non-fungible tokens in the same contract. This is useful for games where you might have both unique items and stackable resources like gold coins. ERC-777 tries to improve on ERC-20 with better functionality. ERC-4626 standardizes yield-bearing vaults. The ecosystem keeps evolving.

But here's what matters philosophically. Standards are acts of coordination. They're agreements that reduce complexity and expand possibility. When everyone speaks the same language, you can have more interesting conversations. When everyone uses the same infrastructure, you can build taller buildings.

The blockchain space sometimes gets accused of being all hype and no substance, and there's some truth to that criticism. But token standards are pure substance. They're the unglamorous plumbing that makes everything else possible. They're why you can move tokens between platforms without thinking about it. They're why new applications can immediately support thousands of existing tokens. They're why developers can build composable systems where smart contracts interact with each other seamlessly.

The lesson here extends beyond crypto. In any ecosystem, the shared infrastructure matters more than the individual participants. The rules of the game shape what games become possible. The standards you adopt determine what innovations you can build.

When you hear about a new token, one of the first questions you should ask is what standard it follows. That tells you where it'll work, what it's meant to represent, and how it fits into the broader ecosystem. That's not exciting. But it's essential.

See you Saturday.

Standards don't constrain creativity—they create the common ground where creativity becomes collaboration.