Simply put: mutable NFTs can be modified by their creator at any time. Immutable NFTs, on the other hand, can't ever be altered.
Wait... aren't all NFTs permanent and uneditable?
Not really. 🤯 Some are, some aren't.
All NFTs live on the blockchain, that's true. But an NFT is not its 🖼 image. The NFT is just the container, and the images are often stored elsewhere.
💡 Let's think of it this way:
The NFT is just a 📃 "certificate of ownership". It says:
Person X owns the item number 123.
The item number 123 can be found here: ____
And that blank is a 🔗 link to where to find the image associated with the NFT.
✅ If the NFT is good, that image is stored on the 🔒 blockchain, and the link points to somewhere on the blockchain, so no one can edit it, and the image is guaranteed to exist forever on-chain.
❌ But often times, that link just points to random websites the owners can edit at any moment, just as I can edit this website. You own nothing that's outside the blockchain on external third-party services.
💀 Or worse: the website can crash, someone might take it down, or the owners might stop paying for the server costs, and then the NFT will be gone forever, without your permission and no matter what you paid for it.
😵💫 You'll be stuck with a certificate of ownership that certifies you own nothing.
Not all NFTs are created equal.
– 👀 looksmutable.com
P.S.: If you're interested in a more in-depth explanation, here's why your NFT might not be on the blockchain.