Help keep the bad guys out of your account by using both your password and your phone.
Why you should use 2-Step Verification
2-Step Verification adds an extra layer of security to your Google Account, drastically reducing the chances of having the personal information in your account stolen. To break into an account with 2-Step Verification, bad guys would not only have to know your username and password, they’d also have to get a hold of your phone.
GOOGLE SUPPORT SITE via About 2-Step Verification – Accounts Help.