How many times have you created a new account at a website and seen a message that said: “Thank you for creating an account. To activate your new account, please access your email and click the verification URL provided.”
To make this process simpler, Google now using an Internet standard called OpenID which is supported by several email providers, including Yahoo!. Instead of the process above, Yahoo! users who sign up with Google see the page below with a button that sends them to Yahoo! for verification.
Once you click that button, Yahoo! shows you a page to get your consent to share your email address with
Google.
After you agree, you’re done and can start using any Google service, such as Google Groups, Docs, Reader, AdWords, etc. We have found that a much larger number of people complete the email verification process when this method is used.
Source: Google blog
