The IBM's Mainframe is famous for being the world's largest computing platform. Over $90\%$ off all the world's financial transaction still use the Mainframe today. The cloud offers a different approach to the single machine idea. This concept is part of the definition of cloud service; what it means to offer cloud services instead of just remote services. Part of what it means to be "cloud" is to offer several individual services $($compute$,$ networking, and storage$)$ as a group that acts like one service. For example, a thousand compute servers could combine with the help of special software and appear as one big machine. What is this concept called?