What are NFTS?

Depends on who you ask, but we find this description acceptable.

NFTs are also called non-fungible tokens, and they are blockchain-held tokens that represent a unique asset – whether physical or digital. Essentially, NFTs can represent any form of digital file, whether that's a jpeg of a piece of art, a video, or even real estate. Turning these files into 'tokens' and securing them on a blockchain make buying, selling and trading these files efficient and reduce fraud.

Like physical art an NFT can be sold but the artist can retain the copyright, or they can offer it to the buyer, or decide the on a percentage of secondary sales an owner can have.