Seed Phrases and Private Keys

How the phrase, keys and addresses connect

The phrase generates a master key, the master key derives account keys, and each account key produces addresses. That is why a single phrase can restore an entire multi-network wallet on a new device, and why exposing it compromises every address at once.

The words come from a fixed standard word list, so their order is part of the secret and no word may be substituted.

Storage rules that actually hold up

• Write it on paper as you create the wallet, and store it somewhere only you can reach.
• Consider a metal backup for fire and water resistance if the amount justifies it.
• Store a second copy in a separate physical location to survive a single disaster.
• Never store it as a photo, screenshot, note app entry, email draft or cloud document.
• Never type it into any website, chat, form or support ticket.
• Do not split the words across services in a scheme you have not tested end to end.

If a phrase has ever been photographed, typed into a website or stored in the cloud, treat it as compromised: create a new wallet and move the funds.

Passphrases and extra words

Some wallets support an optional additional passphrase, sometimes called a 25th word, which creates an entirely separate set of accounts. It adds protection if someone finds the written phrase, and it adds a second thing you can permanently lose. Use it only with a tested backup plan.

Common misunderstandings

• A wallet app password is not the recovery phrase; it only unlocks that installation.
• Deleting a wallet app does not delete funds, and reinstalling does not restore them without the phrase.
• Support staff never need your phrase — any request for it is an attack, without exception.
• Writing the words in a slightly wrong order is a common and unrecoverable error, so verify the backup.

Sources

• BIP-39: Mnemonic code for generating deterministic keys
• Ethereum developer documentation — Accounts