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Why You Should Never Use the Same Password on Multiple Sites - GeekDad
If you've registered at Marriott as JohnDoe@yahoo.com and you used the same password that you use for your Yahoo mail, it's not difficult for anyone who gets that Marriott login to access your email account. From there, they can get into nearly anything. They might even get into your bank account this way. So how can you be smarter about passwords?