Throughout the 1960s and 1970s, companies realized that strong engineering, design, and manufacturing functions were strong market strategic keys to creating and capturing customer loyalty. clients. As demand for new products increased in the 1980s, these market needs needed to increase their flexibility and responsiveness to adapt existing products and processes or develop new ones to meet customer needs. As manufacturing improved in the 1990s, managers began to notice material and service inputs involving suppliers and their greater impact on an organization's ability to meet customer needs. As a result of these changes, organizations now find it difficult to manage their organizations. First, they must be involved in the management of their network of all upstream businesses that supply directly or indirectly, as well as the network of downstream businesses, which are responsible for the delivery and market service of the product to the end customer. To be successful, managers must realize that they cannot do it alone and must collaborate with the entire supply chain organization on a daily basis. Because supply chain management involves all functions within an organization, managers need to know what a supply chain is, why it is important, and the impact of supply chain management on the success and profitability of the own organization. Today, Wal-Mart tops the list of America's largest companies in the Fortune 500, “with revenue of nearly $345 billion – more than a quarter of a trillion dollars” (Forbs). Wal-Mart's supply chain management is recognized as a key competitive strategy. A supply chain is a system through which organizations provide their products and services to their customers. The network starts with the basic ingredients to start the supply chain, i.e. the suppliers who supply raw materials, ingredients and so on. From there it will transfer supplies to the manufacturer that builds, assembles, converts or supplies a product. The chain now has to get the product to the consumer by transporting the finished product from the manufacturer through a warehouse or distribution center. One example is that Wal-Mart has a nearby distribution center where products are delivered there and then broken down to be delivered to a retail Wal-Mart. “Wal-Mart will assume responsibility for dismantling larger loads and delivering the product to other Wal-Mart stores” (Ehring 1).