If virtualization occurs at application level, OS level and hardware level, then such service in cloud is

When virtualization occurs at the application, OS, and hardware levels in a cloud environment, the service provided is typically categorized under Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS), based on the level of functionality and abstraction offered.

1. IaaS (Infrastructure as a Service): At the hardware level, virtualization allows multiple users to access, configure, and operate the physical infrastructure via virtual machines. This includes the ability to manage storage, networking, and computing resources. Users have control over the OS but not over the hardware.

2. PaaS (Platform as a Service): At the OS level, PaaS provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure and services typically associated with the process. This abstracts much of the system management effort required for setting up environments.

3. SaaS (Software as a Service): At the application level, SaaS delivers software applications over the internet, on a subscription basis. This is highly abstracted from the underlying infrastructure or OS levels, with the service providers managing access, security, performance, and scalability. Users simply use the software without worrying about how it’s hosted or maintained.

In a complete cloud service model, combining IaaS, PaaS, and SaaS, users can choose the level of control and management they require, from the highest level of control in IaaS to minimal