In some cases, a manufacturer may fill customer orders directly known as builds-to-order; that is, a customer order initiates manufacturing. Generally these organisations do not have a retailer, wholesaler, or distributor in its supply chain.

In other cases, such as a mail order company, manufacturers do not respond to customer orders directly. Stocks are maintained in order to fill customer orders.

The supply chain not only includes the manufacturer and suppliers, but also transporters, warehouses, retailers, and customers themselves.

Within each organisation, such as manufacturer, the supply chain includes all functions involved in receiving and filling a customer request.

These functions include, but are not limited to, new product development, marketing, operations, distribution, finance, and customer service.

Think about a customer walking into a retail store to purchase a pint of milk.

The supply chain begins with the customer and their need for milk.