Categories let you group products or sub-categories together in your catalog and provide more control over your properties, such as price. You can set pricing rules for one category without setting them for other categories. Each category is an individual instance of a category definition.
Each category and product can have one default category. The default category provides a canonical path to a child category or product. If a product is in more than one category, and pricing is set at the category level, only the pricing from the primary parent category is applied to the child categories and products. You can set pricing at the category level by using either category-level pricing or a custom catalog price rule on the category.