SaaS, PaaS, IaaS Explained

1. SaaS — Software as a Service

What it is:
SaaS delivers ready-to-use software applications over the internet. You don’t install or manage the software yourself; it’s accessed through a web browser or app.
User responsibility:
You just use the software. The cloud provider manages everything behind the scenes — infrastructure, platforms, software updates, security.
Examples:
Google Workspace (Gmail, Docs), Microsoft 365, Salesforce, Dropbox, Slack.
Use case:
Ideal when you want to quickly use software without worrying about setup, maintenance, or infrastructure.

What it is:
PaaS provides a platform and environment for developers to build, deploy, and manage applications without dealing with the underlying infrastructure.
User responsibility:
You focus on your application code and data. The cloud provider manages the servers, storage, networking, runtime, and middleware.
Examples:
Google App Engine, AWS Elastic Beanstalk, Microsoft Azure App Service, Heroku.
Use case:
Best when you want to develop and deploy apps quickly without worrying about managing servers, OS, or databases.

What it is:
IaaS offers virtualized computing resources like virtual machines, storage, and networks on-demand. You get raw infrastructure you can configure and control.
User responsibility:
You manage the operating systems, applications, middleware, and data. The provider handles hardware, virtualization, and networking.
Examples:
Amazon EC2, Microsoft Azure Virtual Machines, Google Compute Engine, DigitalOcean Droplets.
Use case:
Useful when you want maximum control over your infrastructure but don’t want to buy and maintain physical servers.

Service Model	What You Manage	What Provider Manages	Examples	Ideal For
SaaS	Just use the app	Everything else	Gmail, Salesforce, Slack	End-users who want ready apps
PaaS	Apps and data	Runtime, OS, infra	Heroku, Azure App Service	Developers building apps
IaaS	OS, apps, data	Hardware, networking	AWS EC2, Azure VMs	IT admins needing full control

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