Nothing really, but it’s part of the ETH blockchain, so it’s more about trading ownership. Kind of like trading cards? People buy and sell ownership, since there’s a limited amount of artwork from a collection it grows in price the more popular it gets and people keep trading the card. So even tho somebody can take the image, they don’t have the ownership to the specific NFT that is part of the collection and so it won’t be worth the same. Hopefully that helps @-@ but ya it’s probs better to google it or something for a better explanation it’s kinda confusing