POL is the currency used to make purchases on the Polygon blockchain.
Blockchain copies of books, also called Digital Collectibles or NFTs, must be purchased using the currency for the blockchain on which these copies are minted and where the purchase is validated.
Unlike regular digital books, Digital Collectibles are created during the minting process by a blockchain transaction, and each resale is tracked and validated on this digital ledger. The currency must match the blockchain. For example, a Digital Collectible minted and validated on the Polygon blockchain must be paid for using POL. A digital collectible minted and validated on the Ethereum blockchain must be paid for using ETH.
