Metadata is basically is a JSON file that contains all the information about your NFT. This information is NOT stored in the Blockchain, metadata is usually stored off-chain and that's why it is very important to store this information on a decentralized file storage where the files cannot be modified. NFT Yard utilizes InterPlanetary File System (IPFS). NFT Yard token smart contract has a function called TokenURI which = refers to a metadata URL stored in IPFS. More about IPFS...
The file that you upload during the NFT creation is stored like the Metadata on a decentralized file storage IPFS. When the NFT is created NFT Yard will add a reference on the metadata file to the location of the media in IPFS such as jpg, png, gif, or svg file. More about IPFS.
Smart Contract Data Indexing
NFT Yard make sure to utilizes the latest Blockchain Technology available and follow the lead projects in the space to make sure the data of the smart contracts are easily accessible and fast. For that we use The Graph Indexing services. More about The Graph.