| Introducing Categories | Adding a Category | Adding Contacts | Viewing a Category | Deleting a Category |
To add contacts to an existing category, work from your list of contacts, not from your list of categories. The All category is a good place to start because it includes all of your contacts. You can add up to 100 contacts to a category, and you can add a contact to one or more categories.
Note: Because the All category shows all contacts all the time, and the Unfiled category shows all contacts that have not been assigned to one of your categories, you cannot actively add contacts to the All or Unfiled categories.
In the Contacts tab, check the box next to each contact that you want to add to the same category.

Click the Add to Category button, then select a category from the pull-down list (or create a new category in which to add the contacts).

Your Yahoo! Address Book displays the selected category with the new contacts and any contacts that were already in the category.

Sending Email to a Category
Of course, one of the reasons you’ve probably created a category is that it allows you to send one email to everyone in the group. To learn how, take a look at the Working With Categories tutorial.
Removing One or More Contacts From a Category
Want to remove a contact from a category? The Working With Categories tutorial shows you how.
Tip: Removing a contact from a category doesn’t delete the contact or remove it from any other categories. At the very least, the contact remains in the All category. To learn how to delete the contact from your Address Book completely, take a look at the Working With Contact Information tutorial.