A passphrase is a sequence of words or other text used to control access to a computer system, program or data. Passphrases are often used to control both access to, and operation of, cryptographic programs and systems.
A user’s account on a website is like a house. The password is the key, and logging in is like walking through the front door. When a user can’t remember their password, it’s like losing their keys. When a user’s account is hacked, it’s like their house is getting broken into.