I’ve been looking for some interesting descriptions about IaaS, PaaS and SaaS to clear this kind of outsourcing infraestructures.
IaaS – Infraestructure as a Service
Infrastructure as a Service is a provision model in which an organization outsources the equipment used to support operations, including storage, hardware, servers and networking components. The service provider owns the equipment and is responsible for housing, running and maintaining it. The client typically pays on a per-use basis.
IaaS systems such as Rackspace or Amazons EC2 allow for businesses to reduce the amount of physical hardware they own, the initial costs of said hardware and the time supporting that goes along with running servers on premises. It can give greater scalability and pricing and can be used to meet demand when high but scaled down when demand drops. IaaS serves the lower level of need for business, the underlying computational power or the storage facilities for large amount of archived data.
PaaS – Platform as a Service
Platform as a Service (PaaS) is a way to rent hardware, operating systems, storage and network capacity over the Internet. The service delivery model allows the customer to rent virtualized servers and associated services for running existing applications or developing and testing new ones.