Cloud service models refer to different categories of services that are provided by cloud computing providers. These models define the level of control and responsibility that the provider and the customer have over the underlying infrastructure and the applications running on it. The three main cloud service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS).

- Infrastructure as a Service (IaaS): IaaS is the basic cloud service model, providing virtualized computing resources over the internet. With IaaS, customers have control over the underlying infrastructure, including virtual machines, storage, and networking. The cloud provider manages the physical hardware, such as servers and data centers, while customers are responsible for managing the operating systems, middleware, applications, and data. This model allows organizations to scale their infrastructure up or down based on their needs without the need for physical hardware investment.
Examples of IaaS providers include Amazon Web Services (AWS) Elastic Compute Cloud (EC2), Microsoft Azure Virtual Machines, and Google Cloud Compute Engine.
- Platform as a Service (PaaS): PaaS provides a higher level of abstraction compared to IaaS. It offers a platform with built-in infrastructure and development tools to build, deploy, and manage applications. PaaS providers handle the underlying infrastructure, including servers, storage, and networking, as well as the runtime environment, middleware, and development tools. Customers focus on developing their applications without worrying about managing the underlying infrastructure.
PaaS is suitable for developers and businesses looking to streamline their application development and deployment processes. It offers scalability, ease of deployment, and automatic management of resources.
Examples of PaaS providers include Heroku, Google App Engine, and Microsoft Azure App Service.
- Software as a Service (SaaS): SaaS is a cloud service model where applications are provided over the internet on a subscription basis. With SaaS, users access software applications hosted on the cloud provider’s infrastructure through a web browser or a thin client. The cloud provider manages all aspects of the infrastructure, including servers, networking, and application software updates, while users only need to have an internet connection and a web browser.
SaaS eliminates the need for users to install and maintain software locally, providing convenience and accessibility from any device or location. Common examples of SaaS applications include customer relationship management (CRM) systems like Salesforce, collaboration tools like Google Workspace (formerly G Suite), and productivity applications like Microsoft Office 365.
Each cloud service model offers different levels of control, flexibility, and management responsibilities. Organizations can choose the most suitable model based on their specific needs, ranging from infrastructure control in IaaS to focusing solely on application usage in SaaS.