🧾 ERC-721: The Original NFT Standard
Deep dive into unique token IDs and transferFrom mechanics
Master ERC-721, ERC-1155, and their differences
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0 / 5 completed🔍 ERC-721: Interface Deep Dive
ERC-721 defines the minimum interface every NFT contract must implement. These functions enable ownership tracking, transfers, and marketplace integration. Understanding them is key to building and interacting with NFTs.
Query Functions
Check ownership, balances, and approvals
Transfer Functions
Move tokens between addresses securely
Approval System
Delegate transfer rights to operators
🛠️ Interactive: Function Explorer
Click any function to see its purpose, parameters, return value, and real-world use case.
Select a function to explore its details and use cases
✅ ERC-721 Strengths
- •Simple: Easy to understand and implement
- •Mature: Battle-tested since 2017
- •Universal: Every wallet/marketplace supports it
- •Clear ownership: One token = one unique asset
⚠️ ERC-721 Limitations
- •One contract = one token type (inefficient for collections)
- •No batch transfers (high gas for multiple NFTs)
- •Can't mix fungible + non-fungible tokens
- •More expensive for large-scale projects
💡 Key Insight
ERC-721's approval system is brilliant: instead of transferring your NFT to a marketplace contract (risky!), you approve the marketplace to transfer it on your behalf. If you change your mind, revoke approval. When it sells, the marketplace executes the transfer. This pattern protects sellers while enabling trustless trading.