The company said on Thursday at least 500 million user accounts were affected by a massive data breach. The hack happened in 2014, when "state-sponsored actor" stole account information, including names, emails, passwords, telephone numbers and answers to some security questions.
So what should you do if you have a Yahoo account?
First and foremost, you'll want to change your password immediately. All Yahoo account holders should also change their security questions and answers.
If your accounts one Yahoo suspects was compromised, you'll be prompted to enter a new password as soon as you log on. If you used that same password on other accounts, change those too.