What is HD wallet?
A hierarchical deterministic wallet, where an unlimited tree of keys is derived from one seed.
Standardised as BIP-32 and friends, HD wallets solved backup: one seed covers every future address, so you back up once rather than after every transaction.
The derivation paths are standardised too, which is why a seed phrase can usually be restored in a different wallet from the one that created it.
Related terms
Seed phrase
Twelve or twenty-four words from which every key in a wallet is derived. Anyone with the words has the coins.
Keys & custodyAddress
A string encoding the conditions under which an output can be spent. Bitcoin's equivalent of an account…
Keys & custodyPrivate key
The secret number that authorises spending from an address. Whoever holds it controls the coins…
This definition is part of the Bitcoin Logical glossary. For the fuller explanation, start with Apprendre, or see the live numbers on Le Signal Bitcoin.