Cloud computing provides on-demand access to shared computing resources and infrastructure over the Internet. It refers to services delivered on-demand via the Internet from large pools of systems that are linked together. There are different types of cloud services including Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). Cloud computing architecture consists of a front end accessed by users and a back end of servers and storage that create the "cloud" of computing services.