What are the categories of Cloud service models ?

Infrastructure-as-a-Service (IaaS)

• IaaS provider provides Cloud infrastructure like, servers, routers, storage and other networking components
• Consumer can deploy and run any software - OS and App
• Consumer does not manage or control the infrastructure, but has control over the OS and deployed applications.

Platform-as-a-Service (PaaS)

• It allows to deploy consumer-created or acquired applications on the Cloud infrastructure.
• The consumer does not manage or control the underlying Cloud infrastructure, such as network, servers, OS, and storage, but controls the deployed applications and possibly the application-hosting environment configurations.
• For PaaS, consumers pay only for the platform software components such as databases, OS instances, and middleware.

Software-as-a-Service (SaaS)

• SaaS allows to use service provider’s applications running on a Cloud infrastructure.
• It is accessible from various client devices through a thin client interface such as a Web browser.
• SaaS reduces the need for infrastructure and manual updates.