Address Book is your mobile Yahoo! Address Book.

Choose Address Book from the starting position of the carousel. You can search for contacts, use their phone numbers to call them, and get driving directions to their address. You can also use Address Book functions in Mail to address a message.

You enter and update your Yahoo! Address Book contacts in a browser after signing in with your Yahoo! account. In particular, you might want to update contacts' phone numbers and addresses with exact information—for example, area codes and house numbers.