Understanding Token Standards: ERC20 vs ERC721 in Ethereum Blockchain

Let's talk about tokens in the Ethereum ecosystem. If you've explored Ethereum, you've likely encountered discussions about tokens—especially ERC20 tokens.

What Are Tokens?

A token on Ethereum is essentially a smart contract that follows specific common rules. It implements a standard set of functions shared by all token contracts, such as:

• transfer(address _to, uint256 _value)
• balanceOf(address _owner)

Inside the smart contract, you'll typically find a mapping like this:

mapping(address => uint256) balances;

This tracks how much balance each address holds.

👉 Learn more about token standards

In simple terms, a token is a contract that:

• Tracks ownership balances
• Provides functions to transfer tokens between addresses

Why Tokens Matter

All ERC20 tokens share the same function names, allowing for uniform interaction. This means:

1. If your application works with one ERC20 token, it works with all of them
2. Adding new tokens requires minimal additional coding
3. Just plug in a new token contract address and your application supports it

Real-World Example: Exchanges

When exchanges add a new ERC20 token, they simply:

1. Add the new smart contract address to their database
2. Use the same transfer logic already implemented

This standardization makes ERC20 tokens incredibly efficient for exchange platforms.

Beyond ERC20: Introducing ERC721

While ERC20 works well for fungible tokens (like currencies), it's not ideal for unique assets like our CryptoZombies. Here's why:

1. Indivisibility: You can't have 0.237 of a zombie
2. Uniqueness: Each zombie has different attributes and values

This brings us to ERC721 tokens—the standard for non-fungible tokens (NFTs).

Key Features of ERC721

• Unique identification: Each token has a distinct ID
• Non-interchangeable: No two tokens are exactly alike
• Whole-unit trading: Must be traded as complete items

👉 Master NFT programming

Practical Implementation

We'll structure our ERC721 implementation as follows:

1. Start with the Solidity version declaration:

   pragma solidity ^0.8.0;

2. Import necessary files:

   import "./zombieattack.sol";

3. Create our inheritance structure:

   contract ZombieOwnership is ZombieAttack {
    // ERC721 implementation will go here
   }

FAQ Section

What's the difference between ERC20 and ERC721?

ERC20 is for fungible tokens (like currencies), while ERC721 is for unique, non-fungible assets (like collectibles).

Can I convert an ERC20 token to ERC721?

No, they're fundamentally different standards with different purposes and implementations.

Why choose ERC721 for game assets?

It preserves the uniqueness and indivisibility of items like characters, weapons, or collectibles.

How does ERC721 benefit developers?

It provides a standardized way to create tradable unique assets without reinventing the wheel.

Can exchanges support ERC721 tokens?

Yes, many major exchanges now support ERC721 tokens for NFT trading.

Is ERC721 only for gaming?

No, it's used for any unique digital asset—real estate, art, certifications, and more.