Cloud computing is an approach to a shared IT infrastructure in which large pools of computer systems are linked together to provide IT services. Cloud computing accesses ‘virtual’ resources, and therefore, is not limited by the power and capabilities of local or remote computers. It is the next generation of enterprise data centers, which operate like the Internet, providing extreme scale and fast access to networked users. Cloud computing offers a simplified, centralized platform for use when needed, lowering costs and energy use. Unlike grid computing, which distributes IT for a specific task, cloud computing is used across an entire range of activities. The platforms can be externally hosted services, but are also used inside companies, especially those which operate globally.