How to verify ownership of NFT

How would I verify that someone is the owner of a particular NFT? For example, let’s say there was a Lebron James NFT from Top Shot (or any NFT). How could an owner of the token verify they were the owner? Is there a API for this?

Hi @dhagler I think about the ownership we have two stages. The first ownership would be amongst the stakeholders of that scene. Let say Lebron James, his club, and NBA. These stakeholders are supposed to have their own specific accounts on the relevant blockchain network. In this case, the relevant blockchain network is FLOW.
If a buyer purchase this Top Shot from the first owner, the whole or part of the ownership would be moved to this new buyer account. So the buyer is supposed to have his/ her own account on the relevant blockchain, let say FLOW.
Please let me know if the explanation was clear enough :slightly_smiling_face:

I’m trying to find the technical specifics. I understand there is some kind of unique identifier for a token on the blockchain. What is that identifier (uri?) and how would I find it for a particular top shot (or any NFT)? Then, once I know the identifier for the token, I want to have the current owner supply some secret info to verify they own it. I don’t want to know the secret info, just that they supplied the correct info to verify