Categories offer a way to give products additional behaviors that cannot be accomplished by product options alone. While it's probably best to take a look at the category settings in your admin, we'll briefly discuss the functionality that categories offer.

• Email Receipts. Email receipts can be generated on a per category basis, and different emails can be configured for customers and for admins. So, if you had a conference registration category but also sold books and CDs, you might want a transaction that included a conference registration to send an email to a store admin (the conference registrar); or to send an extra email to the customer with a schedule and link to the hotel; or to send both emails (as they can be configured independently).
• Default Weight Values. These default values can be overridden by explicitly setting the weight product option, but if you have a category for “Shirts” you could set the default weight to 0.5, while you have another category for “Paperweights” with a default weight of 3. That way you wouldn't have to explicitly set the weight on every product's add-to-cart link or form.
• Taxes. Taxes must be set at the category level. This allows you to have certain products taxed differently from others, which can be useful in a variety of situations.
• Shipping and Handling Fees. Categories can set specific handling fees, as well as shipping methods.
• Customs Values. Customs values (used in shipping calculations) can only be set at the category level.
• Quantity Discounts. While individual products can have quantity discounts, they can also be applied for all products in the cart in a given category.
• Coupon Codes. Coupons can be restricted per category, though this is done on the coupon code admin section, not the category admin section.
• Downloadables. Downloadable products must be added to a category where the shipping method is set to “Downloaded by the customer”.

Using product categories is fairly straightforward if you already understand how FoxyCart's products function. Simply:

1. Create a category in your store's admin.
2. Assign that category to the product in your add-to-cart link or form, where the “category code” (as configured in the admin) is set in the product's category option. So, something like this:

   <a href="https://YOURDOMAIN.foxycart.com/cart?name=A great product&price=5&category=YOUR_CATEGORY_CODE">
   	Buy this Great Product!
   </a>
   <form action="https://YOURDOMAIN.foxycart.com/cart" method="post">
   	<input type="hidden" name="name" value="A great product" />
   	<input type="hidden" name="price" value="5.00" />
   	<input type="hidden" name="category" value="YOUR_CATEGORY_CODE" />
   	<select name="size">
   		<option value="small">Small</option>
   		<option value="medium">Medium</option>
   		<option value="large">Large</option>
   	</select>
   	<input type="submit" value="Buy It Now!" />
   </form>

You'll notice that the category product parameter is optional. If you don't specify a category, the DEFAULT category will be used.

It may not be immediately evident, but if you use the select box at the top of your Category page (in the “Select a Category” fieldset) in your store's admin you'll see an option to add a new category. Doing so will actually make a copy of the category you're currently editing.