Descriptor
A wallet descriptor is a compact text string that records how a wallet generates its addresses - the script type, the public keys involved, and the derivation path. It contains no private key, so it can be stored or shared to rebuild a watch-only view of a wallet without granting the ability to spend.
It is what tells software where to look after a restore, which is why a seed phrase can be correct and still show a zero balance without it. A Seedkeeper stores an optional descriptor alongside a seed phrase - see Storing Seed Phrases.