The first term we will look at is cloud service models.

All workloads in a cloud scenario use resources from an extremely large resource pool that is operated (managed) by you or a cloud service provider. These resources include servers, storage, networks, applications, services, and much more.

The cloud service models describe to what extent your resources are managed by yourself or by your cloud service providers.

Let's look at the available service models. In the following diagram, you will find a comparison of the models and the existing management responsibilities. Areas that are colored in blue are managed by you: all others are the responsibility of your provider:

The offers are mainly categorized into the following service models:

• On-premises: On-premises describes a model in which the user manages all resources alone.
• Infrastructure as a Service (IaaS): IaaS describes a model in which the cloud provider gives the consumer the ability to create and configure resources from the computing layer upwards. This includes virtual machines, containers, networks, appliances, and many other infrastructure-related resources.
• Platform as a Service (PaaS): PaaS gives the consumer an environment from the operating system upwards. So the consumer is not responsible for the underlying infrastructure.
• Software as a Service (SaaS): SaaS is the model with the lowest levels of control and required management. A SaaS application is reachable from multiple clients and consumers, and the owning consumer doesn't have any control over the backend, except for application-related management tasks.