ERC-721 Tokens: Everything to Know

By  Beluga Research July 26, 2023

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  • ERC-721 tokens provide a technical standard on the Ethereum blockchain for creating and managing non-fungible tokens (NFTs)
  • These tokens are unique and cannot be exchanged on a like-for-like basis, making them ideal for representing digital assets like collectibles
  • ERC-721 tokens work through smart contracts on the Ethereum blockchain
  • Advantages of ERC-721 tokens include ownership transparency, interoperability, programmability, fractional ownership and decentralization


ERC-721 tokens provide a technical standard on the Ethereum blockchain for creating and managing non-fungible tokens (NFTs). In the world of cryptocurrencies, the ERC-721 token stands out as a groundbreaking innovation.

ERC-721 is a technical standard on the Ethereum blockchain that enables the creation and management of non-fungible tokens. Unlike fungible tokens, which are interchangeable and have equal value, ERC-721 tokens are unique and cannot be exchanged on a like-for-like basis. Each ERC-721 token possesses its own distinct characteristics, making it ideal for representing digital assets such as collectibles, virtual real estate and in-game items.

A Brief History

The concept of non-fungible tokens predates the introduction of ERC-721. In 2012, the Colored Coins project attempted to create unique digital assets on top of the Bitcoin blockchain.

However, it was the launch of CryptoKitties in late 2017 that brought non-fungible tokens into the mainstream. CryptoKitties, a virtual collectible game built on Ethereum, allowed users to buy, sell, and breed unique digital cats represented as ERC-721 tokens. The game's immense popularity congested the Ethereum network and highlighted the potential of non-fungible tokens.

What are ERC-721 Tokens?

ERC-721 tokens are implemented as smart contracts on the Ethereum blockchain. Each ERC-721 token contract represents a collection of unique tokens, and each token within the contract has a distinct identifier (ID). These tokens can be owned, transferred, and traded by users. The smart contract defines the rules and functionalities associated with the tokens, including ownership, transferability, and metadata storage.

ERC-721 tokens have found diverse applications beyond virtual collectibles. They are utilized for digital art, enabling artists to tokenize and sell their creations directly to collectors. Real estate can be represented as ERC-721 tokens, facilitating fractional ownership and efficient property transfers. Additionally, gaming platforms leverage ERC-721 tokens to create unique in-game assets, enhancing player experiences and enabling secondary maAspects

Getting Started

To understand ERC-721 tokens, it's important to have a basic understanding of Ethereum and the concept of tokens. Ethereum is a blockchain platform that enables the creation and execution of smart contracts. These smart contracts are self-executing agreements with the terms of the agreement directly written into code. Tokens, on the other hand, are digital assets that can represent various things, such as currencies, assets or even virtual goods.

ERC-721 tokens, also known as non-fungible tokens (NFTs), are a specific type of token standard on the Ethereum blockchain. Unlike ERC-20 tokens, which are fungible and can be exchanged on a one-to-one basis, ERC-721 tokens are unique and cannot be exchanged on a like-for-like basis. Each ERC-721 token has a distinct value and properties, making them ideal for representing one-of-a-kind assets in the digital world.

Unique Aspects

One of the key aspects that sets ERC-721 tokens apart is their indivisibility. Unlike traditional cryptocurrencies or even ERC-20 tokens, which can be divided into smaller units, ERC-721 tokens are indivisible and cannot be split. Each token is a whole entity, representing a unique item or asset. This indivisibility makes ERC-721 tokens particularly suited for representing rare collectibles, digital art, virtual real estate and other unique assets in the digital realm.

Another unique aspect of ERC-721 tokens is their ability to store metadata on-chain. Each token can have associated metadata, such as a name, description, image or other relevant information. This metadata is typically stored using the InterPlanetary File System (IPFS) or similar decentralized storage solutions. By storing metadata on-chain, the ownership and characteristics of ERC-721 tokens can be easily verified and accessed by anyone, ensuring transparency and immutability.

ERC-721 tokens also introduce the concept of ownership and transferability in the digital world. Each ERC-721 token is associated with a specific Ethereum address, representing the owner of the token. This ownership can be transferred from one address to another through a transaction on the Ethereum blockchain. This opens up a whole new world of possibilities, enabling the trading, gifting, and auctioning of unique digital assets in a secure and transparent manner.

Furthermore, ERC-721 tokens have paved the way for the emergence of decentralized marketplaces and platforms. These platforms provide a venue for users to buy, sell, and trade ERC-721 tokens directly without the need for intermediaries. This decentralized nature ensures that ownership and transactions are controlled by the users themselves, reducing the risk of censorship, fraud, or manipulation. It also enables creators and artists to monetize their digital works directly, without relying on traditional gatekeepers.


  • Ownership and Provenance . ERC-721 tokens provide a transparent and immutable record of ownership and provenance for digital assets. Each token is unique and can be traced back to its original creator or owner, ensuring authenticity and preventing fraud.
  • Digital Collectibles . One of the most prominent use cases for ERC-721 tokens is the creation and trading of digital collectibles. These tokens enable the representation of rare and valuable items in the digital realm, such as virtual trading cards, in-game assets, or unique pieces of digital art. With ERC-721 tokens, individuals can prove ownership of these digital collectibles and trade them securely on blockchain platforms.
  • Interoperability . ERC-721 tokens are built on the Ethereum blockchain, which is widely supported by various wallets, exchanges, and decentralized applications (dApps). This interoperability allows for seamless integration and compatibility with existing Ethereum infrastructure, fostering a vibrant ecosystem for ERC-721 token development and usage.
  • Programmability . ERC-721 tokens can be programmed with smart contracts, enabling developers to define specific rules and functionalities for each token. This programmability opens up a range of possibilities, such as creating tokens with unique characteristics, implementing royalties for token creators, or enabling complex interactions between tokens and Dapps.
  • Fractional Ownership . ERC-721 tokens can be divided into smaller fractions, allowing for fractional ownership of valuable assets. This feature enables broader access to high-value items that may have been previously out of reach for many individuals. Fractional ownership can also facilitate investment opportunities in rare collectibles or real-world assets.
  • Decentralization . ERC-721 tokens are decentralized, leveraging underlying blockchain technology to ensure transparency, security and censorship resistance. By eliminating the need for intermediaries, such as centralized marketplaces or auction houses, ERC-721 tokens empower individuals to directly transact and interact with digital assets in a peer-to-peer manner.


  • Scalability . As with many blockchain-based applications, scalability remains a challenge for ERC-721 tokens. The Ethereum network, on which ERC-721 tokens are primarily built, has experienced congestion and high transaction fees during periods of heavy usage. These limitations can hinder the widespread adoption and efficient trading/.
  • Lack of Standardization . While ERC-721 provides a widely adopted standard for non-fungible tokens, there is still a lack of full standardization across all aspects of token implementation. This lack of standardization can lead to interoperability issues between different ERC-721 token contracts and platforms, potentially limiting the seamless transfer and usage of tokens across various ecosystems.
  • Complexity . Developing and interacting with ERC-721 tokens can be more complex compared to traditional cryptocurrencies. The unique characteristics and programmability of ERC-721 tokens require a deeper understanding of smart contracts and blockchain technology. This complexity may act as a barrier to entry for individuals or developers who are not familiar with these concepts.
  • Regulatory Challenges . As ERC-721 tokens gain popularity, regulatory frameworks around digital assets are still evolving. The classification and treatment of these tokens under existing regulations can be ambiguous, leading to regulatory uncertainties and potential compliance challenges for businesses and users involved in ERC-721 token transactions.
  • Environmental Impact . Like many blockchain-based systems, the energy consumption associated with the Ethereum network has raised concerns regarding its environmental impact. The energy-intensive consensus mechanism used in Ethereum, known as proof-of-work, contributes to carbon emissions and energy consumption. As a result, the environmental sustainability of ERC-721 tokens and blockchain technology as a whole is a subject of ongoing debate and exploration.