> For the complete documentation index, see [llms.txt](https://docs.non-obvious.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.non-obvious.ai/template-library/smart-contracts.md).
# Smart Contracts
📌 ERC721
A standard for non-fungible tokens (NFTs), allowing each token to be unique and individually owned and traded.
📌 ERC721A
An optimized version of ERC721, reducing gas costs for minting multiple NFTs in a single transaction.
📌 ERC1155
A multi-token standard supporting both fungible and non-fungible tokens, allowing batch transfer and streamlined contract management.
📌 Soulbound
A concept for tokens that are non-transferable and permanently tied to a single owner, representing immutable attributes or qualifications.
📌 ERC6551
A contract standard for creating and managing accounts that can hold various tokens and execute transactions.
📌 Fractional
A contract that allows NFTs to be fractionalized into smaller, tradable parts, often represented as ERC20 tokens.
📌 UpgradableNFTContract
A contract for NFTs that can be upgraded post-deployment, ensuring flexibility and adaptability to future changes or improvements.