Cloud computing services are generally classified into different models based on what type of resources are provided to the user.
The three primary service models are:
A. Infrastructure as a Service (IaaS)
IaaS provides virtualized computing resources such as servers, storage, and networking over the internet.
Instead of purchasing physical hardware, organizations rent IT infrastructure on a pay-as-you-go basis.
The cloud provider manages the hardware, while users install and manage their own operating systems, applications, and middleware.
- Examples: Amazon EC2, Microsoft Azure Virtual Machines, Google Compute Engine.
- Advantages: High scalability, reduced hardware costs, and flexibility.
- Limitations: Users still need technical expertise to manage software and systems.
B. Platform as a Service (PaaS)
PaaS provides a platform that includes infrastructure, development tools, database management systems, and middleware—allowing developers to build, test, and deploy applications without managing the underlying hardware.
The cloud provider handles infrastructure, operating systems, and runtime environments, while users focus only on application development.
- Examples: Google App Engine, Microsoft Azure App Services, Heroku.
- Advantages: Faster development, lower operational overhead, and easy collaboration.
- Limitations: Less control over the underlying infrastructure and potential vendor lock-in.
C. Software as a Service (SaaS)
SaaS delivers fully functional applications over the internet that are ready to use without installation or maintenance.
Users can access these applications through a web browser or mobile app, and the provider manages everything—from infrastructure to security updates.
- Examples: Google Workspace (Gmail, Docs), Microsoft 365, Dropbox, Zoom.
- Advantages: No need for local installation, automatic updates, and accessibility from anywhere.
- Limitations: Limited customization and dependence on the provider’s uptime.
D. Additional Service Models (Emerging)
- Function as a Service (FaaS) / Serverless Computing – Executes code in response to events without managing servers (e.g., AWS Lambda).
- Backend as a Service (BaaS) – Provides backend cloud storage, authentication, and APIs for mobile and web apps (e.g., Firebase).
