What is IaaS vs PaaS vs SaaS

Short answer

IaaS provides infrastructure; PaaS provides a development platform; SaaS delivers ready-to-use applications.

Key differences

• IaaS: You manage OS, middleware, and apps; provider manages virtualization and hardware. Example: AWS EC2.
• PaaS: You manage apps and data; provider manages runtime, middleware, and OS. Example: Heroku, Google App Engine.
• SaaS: Provider manages everything; you just use the application. Example: Gmail, Salesforce.

When to use each

• IaaS: Maximum control, custom environments, lift-and-shift migrations.
• PaaS: Faster development, managed scaling, reduced operational overhead.
• SaaS: Standard business functions like email, CRM, and collaboration.