ERC-1155 (sometimes called ERC1155) is a token standard on the Ethereum blockchain that enables the creation and management of multiple tokens of different types within a single smart contract. Introduced by Enjin in late 2017, ERC-1155 was designed to address limitations present in earlier standards like ERC-20 (used for fungible tokens) and ERC-721 (used for NFTs). This innovative approach allows developers to create both fungible and non-fungible tokens while streamlining gas costs and simplifying transactions. This token standard is particularly beneficial for gaming decentralized applications (dApps), where various types of in-game assets need to be represented and managed. By utilizing a single contract, developers can reduce the complexities associated with deploying multiple contracts, thereby improving efficiency and usability within dApps.

One of the key benefits of the ERC-1155 standard is that it allows for the creation of both fungible and non-fungible tokens (NFTs) within a single smart contract, rather than having to create separate smart contracts for each type of token. This can simplify the development process and reduce gas fees for users, as multiple tokens can be transferred in a single transaction.

Additionally, the ERC-1155 standard allows for the creation of semi-fungible tokens, a type of token that has some level of uniqueness but can still be exchanged for other tokens of the same type. Usually, a semi-fungible token is fungible at first (e.g., identical loot boxes or event tickets), but after being redeemed or interacted with, it can become non-fungible, meaning it holds unique properties and is no longer interchangeable. Allowing a token to transition between fungibility states, which can be useful in gaming, ticketing, and digital assets, is a unique feature of ERC-1155.

The ERC-1155 standard defines a set of functions that allow for the creation, transfer, and management of both fungible and non-fungible tokens. These functions include safeTransferFrom, which allows for the transfer of tokens between accounts, and mint, which allows for the creation of new tokens. The ERC-1155 standard also includes a uri function, which allows for the attachment of metadata to each token, such as a name, description, or image.

The ERC-1155 standard supports batch transfers, enabling users to send multiple tokens in a single transaction using the safeBatchTransferFrom function. This capability significantly reduces transaction costs and enhances user experience.

An ERC-1155 smart contract is able to manage multiple tokens at the same time using a unique identifier called a tokenId, a unique value that is assigned to each token when it is created, and it is used to identify the specific token within the smart contract. In an a smart contract, the tokenId is a parameter that is passed to the smart contract's functions to identify the specific token being transferred, minted, or managed. For example, when transferring a token from one account to another, the safeTransferFrom function would include both the from and to addresses, as well as the tokenId of the token being transferred. This architecture makes token management a breeze, allowing for lower gas fees during transactions.