There are three types of service modules in cloud − IaaS, PaaS, and SaaS.
IaaS stands for Infrastructure as a Service. IaaS provides users with the capability to excellerate processing, storage, provisioning, and network connectivity on demand. By Using this service module, the customers can develop their own applications on its resources.
PaaS stands for Platform as a Service. In this models, the service providers give various services like databases, queues, work-flow engines, backlogs, e-mails, etc. to their customers. The customers can use these components for building their own applications. The services, availability of resources and data backup are handled by the service providers that help the customers to focus more on the functionality of their applications.
SaaS stands for Software as a Service. As the name itself suggests, in this Module, the third-party providers give the end-user / their Customer these Module applications with some administrative capability at the application level, that can be described ability to create and manage their users of this Models. Besides, some level of customizability is also allowed. For example, the customers can use their own Business / Firm / corporate logos, colours, etc