Extended Public Key (Xpub)

An extended public key (xpub) is a special type of public key used in Hierarchical Deterministic (HD) wallets, following the BIP 32 standard for Bitcoin. With an xpub, you can generate many unique public addresses from a single source, which makes it possible to receive funds at new addresses without exposing your private keys.

Wallets often use xpubs automatically to create fresh addresses for every transaction. Sharing your xpub allows trusted services to generate addresses on your behalf, such as for payment processing or monitoring incoming transactions. However, giving out your xpub means those parties can track all past and future transactions for that wallet, which can compromise your privacy. For this reason, only share your xpub with services or people you trust.

It's important to note that an xpub cannot be used to spend or steal your bitcoin—private keys remain secure. However, if someone obtains your xpub, they’ll have full visibility into your wallet's transaction history. Xpub keys always begin with “xpub” followed by a long alphanumeric string. This feature is especially helpful for receiving bitcoin directly to cold storage, since you can keep the xpub online to make new addresses while your private keys stay safe offline.