The traditional pillars if Cloud Computing are Software as a Service (SaaS), Platform as a Service (PaaS) and Infrastructure as a Service (IaaS).
Infrastructure as a service (IaaS) is a form of cloud computing that provides virtualized computing resources over the internet. In an IaaS model, a cloud provider hosts the infrastructure components traditionally present in an on-premises data center, including servers, storage and networking hardware, as well as the virtualization or hypervisor layer.
Platform as a service (PaaS) is a cloud computing model in which a third-party provider delivers hardware and software tools - usually those needed for application development - to users over the internet. A PaaS provider hosts the hardware and software on its own infrastructure. A PaaS provider builds and supplies a resilient and optimized environment on which users can install applications and data sets. Users can focus on creating and running applications rather than constructing and maintaining the underlying infrastructure and services.
Software as a service (SaaS) is a software distribution model in which a third-party provider hosts applications and makes them available to customers over the Internet. SaaS removes the need for organizations to install and run applications on their own computers or in their own data centers. This eliminates the expense of hardware acquisition, provisioning and maintenance, as well as software licensing, installation and support.
These traditional pillars now support such a range of services that IT, and business, is getting into the 'Everything as a Service' era. Gartner foresees continuing growth in all sectors (and particularly IaaS, PaaS and SaaS), reflecting the seemingly relentless march of public cloud adoption. ere's a listing of IT components and business processes that are available as cloud-based services, and the key providers: