In most cases it's,
A. Just a link which happens to be a jpg. Which means it the website wants to change the jpg they can or if the website goes down it points nowhere.
Or B. Just a hash, which might supposed to be a unique representation of a specific image, but really is just a string of characters, so different sites might disagree what that image is.
If you're talking about an IPFS hash, That's a hash based on the image's content on a very specific network. The same image content will always hash to the same key.
I'm looking for a rendition of the Sistine Chapel with God as Danny Devito and Christopher Lloyd as Adam, like it was in the Taxi days, ideally done in oils. All I've got is a buck, but my social account has followers. If I post it, you'll get exposure. What can you do for me?
NFT's were actually a very clever plot put together by us starving artists to combat the hordes of choosing beggars that infest the internet. We all knew it was a scam, just like limited edition glichee prints, but there hasn't been a time in history when artists made enough money not to have to scam folks to survive, so we figured we were more than justified taking the tech-bros for a ride.