A product line is a cluster of products that are marketed under the same brand umbrella, all sold by the same company. It is cost-effective for a company to cluster products into product lines, since they can build brands across a number of products. One marketing campaign can then be applied to each product line. It is generally safer to add a product to an existing product line than to create a free-standing product, since customers tend to buy repeatedly within the same brand, and so would favor a product within a product line over a free-standing product.
Companies may create product lines within certain markets and then rebrand them in other markets to suit local tastes. Thus, an automobile product line in Asia may have quite different features than one in South America, even though both lines are owned by the same company.