What is the meaning of the concept Next process is the customer?

American quality pioneer, W. Edwards Deming gave U.S. quality and productivity seminars in Japan and taught that ,in a typical business system,meeting and exceeding the customers' requirements is the task of everyone within an organization. And he dramatically broadened the definition of "customer" to include both internal and external customers.

Each person or step in a production line or business process was to be treated as a "customer" and to be supplied with exactly what was needed, at the exact time needed . This was the origin of Deming's principle , "the next process is the customer." The Japanese phrase for this, atokotei WA o-kyakusama, became one of the most significant expressions in JIT, because in a pull system it means the preceding process must always do what the subsequent process says.