What is cloud computing?

Answer

Gartner defines cloud computing as "a style of computing in which massively scalable IT-related capabilities are provided 'as a service' using Internet technologies to multiple external customers." Beyond the Gartner definition, clouds are marked by self-service interfaces that let customers acquire resources at any time and get rid of them the instant they are no longer needed. The cloud is not really a technology by itself. Rather, it is an approach to building IT services that harnesses the rapidly increasing horsepower of servers as well as virtualization technologies that combine many servers into large computing pools and divide single servers into multiple virtual machines that can be spun up and powered down at will.