> For the complete documentation index, see [llms.txt](https://nft-standards.gitbook.io/nft-standards-wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nft-standards.gitbook.io/nft-standards-wiki/standards/eip165-standard-interface-detection.md). # EIP165 Standard Interface Detection ## Simple explanation Interface Detection Standard creates a simple way for a contract to tell consumers (website or contracts or application) that it supports a specific set of functionalities. For example ERC21 metadata or EIP1155 etc. This EIP Standardize following: 1. How interfaces are identified 2. How a contract will publish the interfaces it implements 3. How to detect if a contract implements ERC-165 4. How to detect if a contract implements any given interface ## Functions `interface`\ Interfaces are identified by set of function selectors which are defined by the Ethereum ABI. It is a subset of Solidity's concept interfaces which defines return types, mutability and identifier. `0x01ffc9a7`\ Interface identifier for this interface. You can calculate this by running `bytes4(keccak256('supportsInterface(bytes4)'));` or using the `Selector` contract "How to Detect if a Contract Implements ERC-165 1. The source contract makes a `STATICCALL` to the destination address with input data: `0x01ffc9a701ffc9a700000000000000000000000000000000000000000000000000000000` and gas 30,000. This corresponds to `contract.supportsInterface(0x01ffc9a7)`. 2. If the call fails or return false, the destination contract does not implement ERC-165. 3. If the call returns true, a second call is made with input data `0x01ffc9a7ffffffff00000000000000000000000000000000000000000000000000000000`. 4. If the second call fails or returns true, the destination contract does not implement ERC-165. 5. Otherwise it implements ERC-165. How to Detect if a Contract Implements any Given Interface 1. If you are not sure if the contract implements ERC-165, use the above procedure to confirm. 2. If it does not implement ERC-165, then you will have to see what methods it uses the old-fashioned way. 3. If it implements ERC-165 then just call `supportsInterface(interfaceID)` to determine if it implements an interface you can use."- EIP ## Further reading * Full implementation: