The number and type of products displayed by retailers for purchase by consumers. The two major components of an assortment strategy are the depth of products offered (how many variations of a particular product a store carries), and the width of the product variety (how many different types of products a store carries).
A deep assortment of products means that a retailer carries a number of variations of a single product (the opposite being a narrow assortment); a wide variety of products means that a retailer carries a large number of different products (the opposite being a narrow variety).
Retailers face a trade-off when determining an assortment strategy. Choosing a wide variety and a deep assortment simultaneously requires a large amount of space, and is typically reserved for big box retailers. Stores with smaller spaces may choose to specialize in a certain type of product and offer consumers a variety of colors and styles, while others may offer a deep assortment of products but a narrow variety (convenience stores, for example).