Cloud Computing can be divided by two main criteria. The first criterion is service models, and another criterion is deployment models.
For service model criterion, cloud computing can be divided into three types which are software as a service (SaaS), platform as a service (PaaS) and infrastructure as a service (IaaS)
Software as a Service (SaaS)
The first service model, software as a service, likes an online application. Service provider is responsible to provide, manage and maintain all of service, such as infrastructure, platform and software. Also, customers are not acceptable to manage the service. However, some applications allow consumers to configure minor features.
Customers are able to use applications that service owner provided via web browser or thin client.
Examples of software as a service are Google Apps, such as Gmail and Google docs, and Apple iCloud.
Platform as a Service (PaaS)
The second service model, platform as a service, is a service that was improved from software as a service. Customers are not able to use only software that delivers from service provider, but they are able to organize some configurations, including produce their own new applications.
Platform as a service is able to break down into three main types. These types are called add-on application platform, stand-alone application platform and open platform. The first type is that consumers could configure application that provided and also add some features. The second type is that consumers are able to create their own application. However, they have to use the environment that service provider required. The third type is nearly same as the previous one, but consumers are able to set up their own environment.
Examples of platform as a service are Google App Engine and Microsoft Windows Azure.
Infrastructure as a Service (IaaS)
The third service model, infrastructure as a service, is a service that...