, create documents, and store backup copies of documents. Organizations that are hesitant to place critical applications under the control of outside providers are taking advantage of new technologies to support centralized applications that require less space and energy, and fewer full-time staff members to support them. They make their data center operations more efficient by centralizing services and eliminating those in branch offices, which reduces the required staffing. They have also embraced server virtualization, whereby multiple applications and operating systems are installed on a single server. This decreases the number of servers that need to be supported, which saves space and energy consumption. Higher-speed, more-reliable networks are important factors that have enabled these efficiencies. As a result of network-based services, network criticality has increased, as have the need for higher speeds and capacity. Consumers and commercial organi- zations take network availability for granted. However, carriers have invested heavily in upgrading landline networks to meet these demands for capacity and connectivity. Mobile and landline carrier consolidation is occurring worldwide, and many pro- viders have global and nationwide operations. In parts of the world, two or three large providers control the majority of networks. This low level of competition results in high prices for Internet access and decreases the impetus for network innovation. By contrast, in countries such as India, which has a large number of mobile carriers, com- petition has resulted in low-priced mobile services. Low prices, however, have led to low profit margins. The affordability of mobile services and the growing percentage of the population worldwide with access to the Internet pose difficult issues. For example, in countries with robust networks, commercial organizations expect employees to be always avail- able via e-mail and text messaging. It has become more difficult to "tune out" and take a real break from work. Moreove