nft-standards

# NFT Standards Master ERC-721 and ERC-1155 NFT standards, metadata best practices, and advanced NFT features. ## When to Use This Skill - Creating NFT collections (art, gaming, collectibles) - Implementing marketplace functionality - Building on-chain or off-chain metadata - Creating soulbound tokens (non-transferable) - Implementing royalties and revenue sharing - Developing dynamic/evolving NFTs ## ERC-721 (Non-Fungible Token Standard) ```solidity // SPDX-License-Identifier: MIT pragma solidity ^0.8.0; import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol"; import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; import "@openzeppelin/contracts/utils/Counters.sol"; contract MyNFT is ERC721URIStorage, ERC721Enumerable, Ownable { using Counters for Counters.Counter; Counters.Counter private _tokenIds; uint256 public constant MAX_SUPPLY = 10000; uint256 public constant MINT_PRICE = 0.08 ether; uint256 public constant MAX_PER_MINT = 20; constructor() ERC721("MyNFT", "MNFT") {} function mint(uint256 quantity) external payable { require(quantity > 0 && quantity <= MAX_PER_MINT, "Invalid quantity"); require(_tokenIds.current() + quantity <= MAX_SUPPLY, "Exceeds max supply"); require(msg.value >= MINT_PRICE * quantity, "Insufficient payment"); for (uint256 i = 0; i < quantity; i++) { _tokenIds.increment...