IAAS

Infrastructure as a services is part of cloud computing along with pass and saas that provide virtualized hardware resource over the internet. Iaas platform provides on demand highly scale able solutions
IaaS customers pay on a per-use basis, typically by the hour, week or month. Some providers also charge customers based on the amount of virtual machine space they use. This pay-as-you-go model eliminates the capital expense of deploying in-house hardware and software. However, users should monitor their IaaS environments closely to avoid being charged for unauthorized services.

PAAS

platform as a service is a cloud computing model that delivers software and hardware tools over the internet, tools are needed for application development. In return Paas helps users to avoid in house installation of tools for development.

SAAS

software as a service is software distribution model in which software is hosted centrally and made available to client through thin clients or web browsers. Saas ensures that customer data is readily available to them for anywhere around the world over the internet. The advatages of saas over traditional models ( software as a product) are
• easier administration
• automatic updates and patch management
• compatibility: All users will have the same version of software.
• easier collaboration, for the same reason
• global accessibility.