When a user creates a blockchain wallet instead of using a single password, a mnemonic seed is used. A mnemonic seed is a random string of English words that functions similarly to a password. If a user loses access to their phone or device, the seed can be used to restore the wallet, including any cryptocurrencies. Unlike passwords, the blockchain wallet provider does not store users' mnemonic seeds. These seeds follow industry standards, meaning the wallets can be recovered even if the company goes out of business. However, this means if you lose your mnemonic seed phrase and lose access to the device your wallet is on you will not be able to get access to that wallet again - so please keep the seed phrase backed up, safe and secure..