What is an HD Wallet?
A Hierarchical Deterministic (HD) wallet generates an entire tree of private keys from a single master seed — normally a BIP-39 seed phrase. “Deterministic” means the same seed always produces the exact same tree of keys; “hierarchical” means keys are organized as parent → child → grandchild levels.
This is why one 12-word backup covers everything:
Seed phrase (12/24 words)
└── Master key
├── Ethereum: account 0, address 0, 1, 2 …
├── Ethereum: account 1 …
├── Bitcoin: native segwit addresses …
└── Solana, and other chains …MetaMask, Ledger, Trezor, Phantom, and Trust Wallet are all HD wallets. When you “create another account” in MetaMask, no new backup is needed — the new address is just another branch of the same tree.
How It Works
- The seed phrase is converted into a binary seed
- Hashing produces a master key and a master chain code
- Child keys are derived layer by layer, each identified by an index
- The exact route from master to a specific address is written as a derivation path like
m/44'/60'/0'/0/0
Why It Matters for Security
- Backup is one-time and total: 12 words = every address the wallet will ever create, on every chain, forever.
- The seed outranks the device: a lost phone or dead hardware wallet is recoverable; a leaked seed phrase is game over. The device is a viewer; the phrase is the wallet.
- Watching-only keys exist: HD wallets can export public branches so a watchtower or accountant can see balances without spending power. Only the private levels can sign.
Common Confusion
Importing the same seed into a different wallet brand can show different addresses — not a bug. If the two wallets use different derivation paths or default chains, they read different branches of the same tree. The funds aren’t gone; they’re under a different path, reachable by a wallet that looks in the right place.