Infrastructure as a Service (IaaS) is one of the three fundamental service models of cloud computing alongside Platform as a Service (PaaS) and Software as a Service (SaaS).
As an alternative to the three tiered classification of cloud based services - Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Sevice (SaaS) - cloud computing can also be classified based upon how the underlying networks are implemented and accessed by the client. The following article provides and overview of the two principle models Public and Private Clouds.
Cloud hosting services provide hosting for websites on virtual servers which pull their computing resource from extensive underlying networks of physical web servers.