Wallet Extended Public Key

A Wallet Extended Public Key, often called an xpub, is a derived key that allows an observer to view all public addresses associated with a master seed without having access to the private keys. This key is incredibly useful for portfolio trackers, accounting software, and watch-only wallets, as it enables the tracking of transaction history and balances across all derived addresses.

Because it is an extended key, it contains the information necessary to calculate all future child public keys, ensuring that the wallet software stays synced with the blockchain. However, it must be handled with care, as leaking an xpub can compromise the privacy of the user by linking all their addresses to a single identity.

It serves as a read-only gateway into the financial activity of an HD wallet.