# Non-fungible tokens (NFTs)

Non-fungible tokens (NFTs) are unique digital assets that are indivisible and cannot be replicated. Unlike cryptocurrencies such as Bitcoin or Ethereum, which are fungible and can be exchanged on a one-to-one basis, each NFT has a distinct value and specific information that sets it apart from other tokens. NFTs are typically used to represent ownership or proof of authenticity of digital or physical items, such as art, collectibles, music, in-game items, and even real estate.

There are several types of NFTs, each serving different purposes and representing different types of assets:

1. **Art NFTs:** Art NFTs represent digital artworks created by artists. These can include images, animations, and other forms of digital art. Art NFTs have gained significant popularity in the art world, enabling artists to tokenize their work and sell it as a unique digital asset.
   * "Everydays: The First 5000 Days" by Beeple - This digital artwork was sold for $69 million at Christie's auction house, making it one of the most expensive NFT artworks to date. [View on Christie's](https://www.christies.com/lot/lot-6118283-6258381/)
2. **Collectibles NFTs:** Collectibles NFTs represent digital collectibles, such as trading cards, virtual pets, or other items that users can collect and trade. These NFTs often have unique attributes or properties that make them desirable to collectors.
   * CryptoKitties - CryptoKitties are digital collectible cats that can be bred and traded. Each CryptoKitty is unique and owned by the user as an NFT. [Visit CryptoKitties](https://www.cryptokitties.co/)
3. **Gaming NFTs:** Gaming NFTs are used in the gaming industry to represent in-game assets, such as characters, skins, weapons, or virtual land. Players can buy, sell, and trade these NFTs, giving them ownership and control over their in-game assets.
   * Axie Infinity - Axie Infinity is a blockchain-based game where players collect, breed, and battle fantasy creatures called Axies. Axies are NFTs that can be bought, sold, and traded. [Visit Axie Infinity](https://axieinfinity.com/)
4. **Utility NFTs:** Utility NFTs provide access or special privileges within a digital ecosystem. For example, they can be used to grant access to exclusive content, membership perks, or voting rights in decentralized autonomous organizations (DAOs).&#x20;
   * ENS Names - Ethereum Name Service (ENS) allows users to create human-readable names for Ethereum addresses. These names are NFTs that can be used as a decentralized identity for sending and receiving cryptocurrency. [Visit ENS](https://ens.domains/)
5. **Real-world Asset NFTs:** NFTs can also represent ownership of real-world assets, such as real estate, luxury goods, or intellectual property. These NFTs can be used to tokenize and trade ownership of physical assets on blockchain platforms.&#x20;
   * The Metaverse Group's Virtual Real Estate - The Metaverse Group sells virtual real estate as NFTs, allowing users to own and develop virtual land in the metaverse. [View on The Metaverse Group](https://themetaversegroup.io/)
6. **Event Tickets NFTs:** NFTs can represent event tickets, providing a secure and transparent way to manage ticketing for concerts, sports events, conferences, and other events.&#x20;
   * NBA Top Shot - NBA Top Shot is an NFT platform where users can buy, sell, and trade officially licensed NBA collectible highlights. Each highlight is a unique NFT representing a specific moment in NBA history. [Visit NBA Top Shot](https://www.nbatopshot.com/)

## ERC-1155 vs ERC-721:

<table><thead><tr><th width="171">Feature</th><th>ERC-1155</th><th>ERC-721</th></tr></thead><tbody><tr><td><strong>Fungibility</strong></td><td>Supports both fungible and non-fungible tokens within the same contract</td><td>Supports only non-fungible tokens</td></tr><tr><td><strong>Batch Transfers</strong></td><td>Allows for batch transfers of multiple tokens in a single transaction</td><td>Requires individual transactions for each token transfer</td></tr><tr><td><strong>Gas Efficiency</strong></td><td>Generally more gas-efficient, especially for batch operations</td><td>Each token transfer requires a separate transaction, potentially higher gas costs</td></tr><tr><td><strong>Complexity</strong></td><td>More complex due to support for multiple token types in a single contract</td><td>Simpler to implement and understand</td></tr><tr><td><strong>Use Cases</strong></td><td>Suitable for use cases with both fungible and non-fungible tokens</td><td>Typically used for applications with unique, non-fungible assets</td></tr></tbody></table>

### OpenSea Examples:

* **ERC-1155**: "The Sandbox" virtual world uses ERC-1155 tokens to represent various in-game assets, including land, characters, and items. Players can buy, sell, and trade these tokens on OpenSea.
  * [The Sandbox on OpenSea](https://opensea.io/collection/the-sandbox)
* **ERC-721**: "CryptoKitties" is a popular example of ERC-721 tokens representing unique digital cats. Each CryptoKitty is a non-fungible token with its own traits and characteristics.
  * [CryptoKitties on OpenSea](https://opensea.io/assets/cryptokitties)

In summary, ERC-1155 is more versatile and efficient for certain use cases that involve both fungible and non-fungible tokens, while ERC-721 is simpler and more straightforward for applications that require only non-fungible tokens.
