Google 2 Step Authentication Review — The Gadgeteer
Working in IT you’d think I’d know better; however, this got me thinking about all the information I have stored in my Google account. Access to my email alone would allow access to other sensitive information, which as a flow on from my emails gives them access to other websites indirectly. Password resets to the email address for other non-Google applications or sites could be performed, as well as the ability to gain access to applications that use your Google account as a “passthrough” login for that application. In addition if you’re part of the “Google-verse” (“luckily” my above friend had just a Hotmail email account ), access to your Google account gives you access to email and all your other Google apps such as Google+, documents, photos, reader, YouTube, and other info. A bit scary really 
Google 2 step authentication works on 2 things, something you know – your password – and something you have – your phone/tablet.