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 email address to create a new message, 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 sign in to 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.