Cryptocurrencies use mnemonic phrases as a master key for a wallet. All the private keys are generated deterministically from the master key. BIP-39 mnemonic ph

Cryptocurrencies use mnemonic phrases as a master key for a wallet. All the private keys are generated deterministically from the master key. BIP-39 mnemonic phrase is a list of 12 or 24 words. It is quite easy to write down on a piece of paper or metal, and/or memorize. Offline hardware wallet is usually used to securely generate and use the key for signing transactions.