= ERC 721
[.readme-notice]
NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/token/erc721
This set of interfaces, contracts, and utilities are all related to the https://eips.ethereum.org/EIPS/eip-721[ERC721 Non-Fungible Token Standard].
TIP: For a walk through on how to create an ERC721 token read our xref:ROOT:erc721.adoc[ERC721 guide].
The EIP consists of three interfaces, found here as {IERC721}, {IERC721Metadata}, and {IERC721Enumerable}. Only the first one is required in a contract to be ERC721 compliant. However, all three are implemented in {ERC721}.
Additionally, {IERC721Receiver} can be used to prevent tokens from becoming forever locked in contracts. Imagine sending an in-game item to an exchange address that can't send it back!. When using <<IERC721-safeTransferFrom,`safeTransferFrom`>>, the token contract checks to see that the receiver is an {IERC721Receiver}, which implies that it knows how to handle {ERC721} tokens. If you're writing a contract that needs to receive {ERC721} tokens, you'll want to include this interface.
Additionally there are multiple custom extensions, including:
* designation of addresses that can pause token transfers for all users ({ERC721Pausable}).
* destruction of own tokens ({ERC721Burnable}).
NOTE: This core set of contracts is designed to be unopinionated, allowing developers to access the internal functions in ERC721 (such as <<ERC721-_mint-address-uint256-,`_mint`>>) and expose them as external functions in the way they prefer. On the other hand, xref:ROOT:erc721.adoc#Presets[ERC721 Presets] (such as {ERC721PresetMinterPauserAutoId}) are designed using opinionated patterns to provide developers with ready to use, deployable contracts.
== Core
{{IERC721}}
{{IERC721Metadata}}
{{IERC721Enumerable}}
{{ERC721}}
{{IERC721Receiver}}
== Extensions
{{ERC721Pausable}}
{{ERC721Burnable}}
== Convenience
{{ERC721Holder}}
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