You probably know by now that you should never use the same password in more than one place, and that each of your passwords should be strong enough to resist an automated attack. Perhaps you use iCloud Keychain, or a third-party password manager such as 1Password or LastPass to generate random passwords, store them, and fill them in automatically. But all that may not be enough if a site suffers a security breach that reveals its users passwords to an attacker--sadly, a frequent occurrence.
