= 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 specifies four interfaces:
* {IERC721}: Core functionality required in all compliant implementation.
* {IERC721Metadata}: Optional extension that adds name, symbol, and token URI, almost always included.
* {IERC721Enumerable}: Optional extension that allows enumerating the tokens on chain, often not included since it requires large gas overhead.
* {IERC721Receiver}: An interface that must be implemented by contracts if they want to accept tokens through `safeTransferFrom`.
OpenZeppelin Contracts provides implementations of all four interfaces:
* {ERC721}: The core and metadata extensions, with a base URI mechanism.
* {ERC721Enumerable}: The enumerable extension.
* {ERC721Holder}: A bare bones implementation of the receiver interface.
Additionally there are a few of other extensions:
* {ERC721URIStorage}: A more flexible but more expensive way of storing metadata.
* {ERC721Votes}: Support for voting and vote delegation.
* {ERC721Royalty}: A way to signal royalty information following ERC2981.
* {ERC721Pausable}: A primitive to pause contract operation.
* {ERC721Burnable}: A way for token holders to burn their own tokens.
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}}
{{ERC721Enumerable}}
{{IERC721Receiver}}
== Extensions
{{ERC721Pausable}}
{{ERC721Burnable}}
{{ERC721URIStorage}}
{{ERC721Votes}}
{{ERC721Royalty}}
== Presets
These contracts are preconfigured combinations of the above features. They can be used through inheritance or as models to copy and paste their source code.
{{ERC721PresetMinterPauserAutoId}}
== Utilities
{{ERC721Holder}}
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