Google has introduced a two-factor authentication security feature for Google email accounts.
The company announced two-factor authentication for its Google Apps customers last year, and the opt-in feature has now been extended to all Gmail account users.
"It's an extra step, but it's one that significantly improves the security of your Google Account because it requires the powerful combination of both something you know - your user name and password - and something that only you should have - your phone," said Nishit Shah, product manager at Google Security, in a blog post.
"Once you enable two-step verification, you'll see an extra page that prompts you for a code when you sign into your account. After entering your password, Google will call you with the code, send you an SMS message or give you the choice to generate the code for yourself using a mobile application," added Shah.
The feature can be used via Google Android, Research in Motion (RIM) Blackberry or Apple iPhone devices.
The service also offers the option to prompt for a mobile verification code every 30 days.