[mortehu]

Excuse my ignorance, because I haven't looked into NFTs too carefully, but how do you decide which blockchain (or even block) is authoritative for a given item? Seems like something like a painting could be sold on an unlimited number of chains? If it's time priority (oldest wins), what's preventing miners from copying artwork from slower chains before they're included in a block?

[delaaxe]

The buying decision originates from the content creator, who will tell you which ones are from him.

NFTs sold on other chains are akin to copies of the Mona Lisa: worthless

[EMM_386]

Good question.

There seem to be ... quite a lot of them.

https://coinmarketcap.com/nfts/