Cloud computing, simply defined, is a set of computing resources and tools delivered over the web as a hosted service. The name cloud computing evolved from the way the Internet has been represented as a cloud in computing discussions. Cloud computing services may be categorized as Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) or Software-as-a-Service (SaaS). Unlike traditional hosting services, cloud computing services are offered on a pay-for-what-you-use basis.