Token Metadata Program
The Token Metadata program is one of the most important programs when working with NFTs. Its main goal is to attach additional data to fungible or non-fungible tokens on Solana.
It achieves this using PDAs that are derived from the address of mint accounts.
Important
Mint accounts are responsible for storing the global information of a token and token accounts store the relationship between a wallet and a mint account.
Metadata Account
Whilst mint accounts contain a few data attributes such as its current supply, they cannot hold standardized data that can be understood by apps and marketplaces. This is why the Token Metadata program offers a metadata account that attaches itself to a mint account via a PDA.
Master Edition
Additionally, the Token Metadata program offers another account specifically for NFTs called the Master Edition account. This account is also a PDA derived from the mint account.
Note
Before creating this account, the Token Metadata program will ensure the special characteristics of NFTs are met. Thus, the existence of the Master Edition account acts as proof of non-fungibility for that mint account.
The Master Edition account includes some additional fields that are not crucial for the main idea. In essence, Metaplex offers the capability to create copy of NFTs, with the Master Edition account serving as proof of whether an NFT is original or a copy.
