There are three cloud computing models:

• Infrastructure as a Service(IaaS)
• Platform as a Service(PaaS)
• Software as a Service(SaaS)

Each of these models provides different levels of control and management.

IaaS gives virtual computation resources via the internet. It offers basic infrastructure services like virtual machines, storage, and networking. The user is responsible for managing operating systems, applications, and data. In the process, provider manages physical hardware and network infrastructure. IaaS is suitable for any business that wants flexible and scalable infrastructure without physically investing in hardware.

PaaS offers a platform where developers can build, deploy, and manage applications and need not bother about the underlying infrastructure. This basically includes development tools, database management systems, middleware, and operating systems. In general, PaaS simplifies the development process by removing the burden of system administration so more time can be given to coding and application logics.

SaaS simply refers to the delivery of software applications over the internet on a subscription basis. Users share the software through a web browser, while the provider is responsible for the underlying infrastructure, software updates, and maintenance. SaaS is especially suitable in the case of end-users who want fully operational applications, such as email and collaboration tools, without being bothered by installation or maintenance.

Therefore IaaS offers infrastructure, PaaS provides a development platform, while SaaS comes with fully managed software applications.