Nowadays many of you may use same password on many sites means if your account of any of those sites got hacked then hackers may have access to your Google Account.So in order to make your Google account more secure Google has introduced an extra level of security for your account.
Google is calling this as 2-step verification that makes your Google Account significantly more secure by helping to verify that you’re the real owner of your account.In this level you had to enter your account password as well as a Secret Code generated by Google Server which you will receive on your phone.
In this what happens that first you have to sign in using you username and password then Google will send a code to your phone and then you have to enter that code to login to your account.You’ll next be prompted to enter your verification code, which you’ll get from your phone. You’ll only have to do this once every 30 days if you so choose.You can also set up one-time application-specific passwords to sign in to your account from non-browser based applications that are designed to only ask for a password, and cannot prompt for the code.
Soon after you turn on 2-step verification, non-browser applications and devices that use your Google Account (such as Gmail on your phone or Outlook), will stop working. You’ll then have to sign in using your username and a special password you generate for this application. (Don’t worry, you’ll only have to do this once for each device or application.)
So to start using this service you have to head toward you Google Account page and then click on Using 2-Step Verification.