Some business models divide the functions into three main categories: producing, selling and supporting. Lesser functions are placed into these larger categories.
According to the University of Kent's website, producing can be divided into the following functions: research and development, production and quality and the logistics of distribution and production. Similarly, supporting includes functions such as human resources, technological support, purchasing and accounting. Other functions are included under selling, like sales and marketing.
Other models do not make the distinctions between the three major functions. For instance, according to the Microsoft website, the main functional areas of a business are finance, sales, warehouse, purchasing, jobs, manufacturing, service, resource planning, human resources and IT. Microsoft further divides each of these functions into smaller ones. For instance, service is divided into other functions like history and order processing.
Companies may have all of these departments or fewer, depending on the size of the company; sometimes departments are combined in smaller companies. For instance, jobs and human resources may be combined into the same department or finance and sales. Other companies do not have research departments, especially companies focused on service areas. Some companies are so large that it is difficult to categorize them readily.