If your like me you might be in the middle of upgrading your Iphone to the latest operating system one thing you will discover is you have to re-input all your saved passwords back into your phone. If your like me it has been a while and even though I knew my Gmail password it just didn't want to take on the phone, which I discovered was due to me enabling 2 factor authentication on my account which Iphone still hasn't got its act together to handle. If this happens to you you will need to login to your google account and generate a application-specific password.
How to generate an application-specific password
Visit your Google Account settings page.
On the left, click Security.
Under the "2-step verification" topic, click Manage your application specific passwords.
1. Under the Application-specific passwords section, enter a descriptive name for the application you want to authorize, such as "Iphone 4s,"
2. Then click “Generate application-specific password" application-specific password creation
3. You'll then see the application specific password you just created and the name you wrote in for the device
Once you click Done, you’ll never see that application-specific code again. But don't panic: You can generate a new one whenever you’re prompted for an ASP by a non-browser device or application -- even a device or application you’ve authorized before.