The mechanisms that make finding a product easier are the most important features in a commerce business. If it's difficult for a customer to find the product that he needs, then he won't buy it even if that product is available in the shop. One of the features is organizing the products into divisions such as product categories. Organizing the products into categories provides easier navigation for the customer.
A product category is attached to products that are similar by one or more characteristics. A product can be assigned to multiple categories, depending on which characteristics are taken into consideration. For example, a shirt is characterized by length of the sleeve, brand, color etc. It can be assigned to ‘Long sleeve’ category but also to ‘Blue’ category in the same time.