Providing an on-line advertising directory which posts and maintains product data and advertisements for buyers, distributors and suppliers in the fields of, accounting, agriculture, business, communication, construction, education, engineering, financial, food service, forestry and wildlife, government, insurance, janitorial and sanitation, library, management, manufacturing, military, mining, personal, real estate, retail, scientific research, transportation, utilities, and wholesale; and computerized tracking of orders, shipment data, sales information, invoices and payments of the aforementioned product data and advertisement for buyers, distributors and suppliers