Pay-per-usage processing from a datacenter service provider. Customers access the computers in the datacenter via private lines or over the Internet and are charged for the amount of computing time they use in CPU seconds, minutes and hours. Also called "on-demand computing," utility computing was originally based on proprietary standards; however, it evolved into "cloud computing," which uses global standard Internet and Web protocols. If the service provider includes the application programs, it is called an "application service provider" (ASP) and falls under the umbrella of "software-as-a-service" (SaaS). See
cloud computing,
ASP and
SaaS.