A user is any person who uses a product or service to solve a problem or obtain a benefit, whether or not they purchase it. Users may consume a product, as in the case of a person using shampoo to clean their hair or eating a potato chip to assuage hunger between meals. Users may not directly consume a product but interact with it over a more extended period, like a family owning a car, with multiple family members using it for many purposes over several years. Products are also employed in producing other products or services, where they may be referred to as input products. For example, steel is an input product used in the production of automobiles. In product development, the user refers to the target market for a particular product or service. Companies often segment their markets by user type to better understand and address the needs of each group. User types can be distinguished by any number of characteristics, including age, gender, income level, occupation, etc. Understanding users and user types are critical for developing successful products and services.