ters to run applications results in less space used and lower facility cooling costs. Although individual servers running virtual operating software are more powerful and require more cooling than less-powerful servers, the reduction in the total number of physical devices results in overall energy efficiency. Virtualization and Cloud Computing Virtualization is a major enabler of cloud computing. Large cloud providers commonly have multiple data centers that maintain replicated copies of all data. If a data cen- ter becomes disabled, another can easily take over its functions. Virtualization makes it less costly and complex for providers to support multiple data centers in differ- ent physical locations. This results in a reduction of physical services, less electrical power, and less cooling; thus, lowering providers' energy costs. Moreover, virtualization enables data centers to support multiple developers by providing a virtual computing platform for each developer while he is logged on to a virtual machine. Multi-core processors enable multiple developers to simultaneously log on to the same physical server. When a developer logs off of his area of the server, computing power is freed up for other uses. Because of security and privacy concerns, large companies often do not want their applications and files on the same physical servers as those of other organizations. In these instances, they can elect to reserve a group of servers for their own use. Amazon refers to this feature as a Virtual Private Cloud. Other providers offer similar features. Not surprisingly, there is an extra monthly fee associated with this service. Single Servers Functioning as Multiple Servers via Virtualization Virtualization as a Green, Efficient Strategy As of October 1, 2010, the town of Framingham, Massachusetts, had a popula- tion of 68,318 people and 8,434 students in 13 schools. According to Adam Seldow, former director of technology for the Framingham Public Schools, there were 40 servers in the school department's data cent