Before we start on the actual topic (the Azure platform), we should clarify some terms related to cloud computing. Knowing these concepts, we will then be in a position to identify individual parts of the Azure platform.

Let's start.

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.

The second term we will look at is cloud deployment models.

Cloud deployment models describe the way in which resources are provided in the cloud.

Which cloud deployment models are available?

Let's look at the following diagram first:

The deployment model based on the on-premises service model is called the private cloud. A private cloud is an environment/infrastructure, built and operated by a single organization, which is only for internal use.

In the context of this book, you should know that the Windows Azure Pack (a free add-on for the Windows server) gives you the opportunity to deploy Azure technologies in a private cloud environment.

The deployment model based on the IaaS and the PaaS service model is called the public cloud. A public cloud is an offer from a service provider (for example, Microsoft Azure), that can be accessed by the public. This includes individuals as well as companies.

There is still a third deployment model available, which is the hybrid cloud. A hybrid cloud combines parts of the private and public clouds. It is defined as a private cloud environment at the consumer's site, as well as the public cloud infrastructure that the consumer uses.

In the context of this book, you should know that Azure Stack (a new offering from Microsoft) gives you the opportunity to build a hybrid cloud environment: