A public HD-wallet key that can derive addresses without revealing private signing keys.
Extended public key is best understood as part of a system rather than as an isolated definition. Its related coordinates show the mechanisms, incentives and historical records that give the term practical meaning.
Extended public key should be evaluated against a concrete threat model: what is protected, from whom, for how long and at what operational cost. A design may remove one dependency while introducing another, so custody, privacy and verification must be judged as a complete system.
Understanding Extended public key helps distinguish a verifiable Bitcoin mechanism or historical record from slogans, products and market narratives.
For the clearest picture, read this entry together with HD wallet, Watch-only wallet, Bitcoin privacy, Derivation path. The reverse links also lead from HD wallet, Watch-only wallet, Address gap limit.
Linked to related atlas coordinates
Grounded in a source record
Explains function and trade-offs
Part of the open Bitcoin knowledge graph