This step by step tutorial will show you how to turn on 2 Factor verification in Gmail which is OFF by default . In my opinion , this feature is very useful for users as it prevents from hacking .Google will ask you for a code , if you try to login from a different location(browsing centre etc) than the one you setup.
Step 1 : Login into your Gmail account .Click downward facing arrow which is present at right corner & navigate into account .
Step 2: Next under security , click Edit to change the status of 2-step verification from OFF to ON.
Step 3: Sign in into Gmail for second time and enable 2 factor verification in your account .
Step 4: That’s it , you have enabled 2 Factor verification in your account .
Note : You can also have codes sent to your backup phone number if your primary phone is unavailable, lost, or stolen.