Difference between IaaS, PaaS,SaaS and On-Premises
Infrastructure as a service (IaaS) is an instant computing infrastructure, provisioned and managed over the internet. for example Virtual Machine(VM). The consumer has full control over the VM and has to maintain Patching, Software Updates, Security, etc.
Platform as a service (PaaS) is a complete development and deployment environment in the cloud, with resources that enable you to deliver everything from simple cloud-based apps to sophisticated, cloud-enabled enterprise applications. You purchase the resources you need from a cloud service provider(Azure, AWS, Google, etc..) on a pay-as-you-go basis and access them over a secure Internet connection.
Software as a service (SaaS) allows users to connect to and use cloud-based apps over the Internet. Common examples are email, calendaring, and office tools (such as Microsoft Office 365).
In short, I am trying to explain it, see the following table.
| Resources |
On-Premise |
IaaS |
PaaS |
SaaS |
| Hosted
applications |
No |
No |
No |
Yes |
| Development tools, database management, Business analytics |
No |
No |
Yes |
Yes |
| Operating systems |
No |
No |
Yes |
Yes |
| Servers and storage |
No |
Yes |
Yes |
Yes |
| Networking firewalls/security |
No |
Yes |
Yes |
Yes |
| Datacenter physical plant/building |
No |
Yes |
Yes |
Yes |
Resources: List of resources that are required for any software service to be live hosted and running
No: means it not managed by Service Provider, you have to manage service and use it.
Yes: means its managed by Service Provider, you have to use the service only.
Service Providers: Azure, AWS, Google, etc..
Bonus points: I'do recommend always think to use PaaS Services and SaaS service over IaaS, here you will get more time to focus on your app development, business logic, and delivery. Everything else will be managed by the service provider for you.