A non-fungible token (NFT) is a unit of data stored on a digital ledger, called a blockchain, that certifies a digital asset to be unique and therefore not interchangeable. Think of a signed baseball card but in the cloud blockchain
You have an autographed version of a code commit from GitHub
GitGallery is able to verify your git commits when you log in via your GitHub account. You simply paste the URL of your git commit to verify.
Once your commit is verified you will be asked to sign your commit using Metamask
When signed, GitGallery will then mint the token on the Polygon blockchain to create the NFT of your code.