Usually, a price comparison website has its own set of categories (taxonomy) into which it recommends you to organize your products.
Although some shopping engines allow uploading products preserving the categories used on the original website (or even leaving the category field empty), this will likely get your products listed under the "Other" category where no one will find them. The Product Feeds add-on allows you to organize your products into categories specific to comparison shopping sites (in addition to the categories you use on your website).
The add-on allows you to assign feed categories to each product separately or multiple products at once.
Assigning Feed Categories to Single Products
To assign feed categories to a single product:
In the Products section of your store's Admin area (Catalog > Products), locate a product you need to assign a feed category to and open it for editing.
Click on the Feed Categories tab:
You will see the form where you can specify the feed categories into which the product you edit must go:
Use the drop-down boxes to select the feed categories for the product.
Click Update to save the changes.
Bulk Assigning Feed Categories to Products
To assign feed categories to multiple products at once:
In the Products section of your store's Admin area (Catalog > Products), select the products you need to assign a feed category to.
Click the Folder icon below the list of products to update feed categories:
You will see a form where you can specify the feed categories into which the selected products must go:
Use the drop-down boxes to select the feed categories for the products.
Click the "Update categories" button to save the changes.
It's also possible to import feed categories for products using the following fields:
nextagId: specify a relevant NexTag category ID
shopzillaId: specify a relevant Shopzilla category ID
pricegrabberId: specify a relevant Pricegrabber category ID
ebayCommerceId: specify a relevant eBay category ID
googleShoppingId: specify a relevant Google Shopping category ID
The field value should be a category ID of a particular comparison shopping site that you can get from the comparison shopping site itself. An alternative way to find a category ID is to assign a category to some product in the X-Cart Admin area and then export this product and check for the relevant category ID in the export file.