ERC 721

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 ERC721 Non-Fungible Token Standard.

Tip	For a walk through on how to create an ERC721 token read our 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. The core interface and the metadata extension are both implemented in {ERC721}. The enumerable extension is provided separately in {ERC721Enumerable}.

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 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 _mint) and expose them as external functions in the way they prefer. On the other hand, 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}}

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}}