The beginnings of cloud technologies go back almost 20 years. Even after the turn of the millennium, large companies such as Amazon, Google, IBM, Yahoo and Co were experimenting with the flexible use of computers over the Internet. At the moment, the focus was primarily on the increasing user base at peak times such as Christmas. Companies such as the online retailer Amazon are striving to serve their customers faster and more efficiently through bundled computers via the Internet.

From these beginnings, today’s cloud technologies finally developed. But what exactly do they actually describe? What service and delivery models for cloud technologies are there now? And what conclusions can be drawn from the rapid development?

What does the term mean?

The use of special IT infrastructure is described with the term “cloud”, in English “cloud”. It is primarily a matter of making IT resources available dynamically via the Internet in the form of an interaction between several servers. Individual service packages are distributed to the respective server so that another server can always take over the tasks in the event of a failure. As a result, the user does not have a precise overview of where his data and applications are located in the cloud, but can be sure of their occurrence at all times. Use is billed according to flexible payment models.

According to a definition by the US National Institute of Standards and Technology (NIST, NIST 2019) from 2012, cloud technologies should also have the following characteristics:

  • On-demand self service: The user can access cloud resources via the Internet at any time.
  • Broad network access: Users can access the cloud using the Internet in combination with well-known mobile devices such as smartphones, computers or tablets.
  • Resource pooling : The performance of the server is bundled and made available to the user so that the user has no influence on individual servers.
  • Rapid elasticity: The storage space and the performance of the cloud can be adjusted almost infinitely.
  • Measured service: The servers are optimized and monitored by the cloud.

Service models of cloud technologies

Service models in the field of cloud technologies have been growing rapidly for over 10 years. Such a model is not only defined by an overview-like description of a service, but also by the parameters required for implementation.

In practice, a distinction is usually made between three different categories, some of which flow into one another.

  • Software as a Service (SaaS),
  • Platform as a Service (PaaS) and
  • Infrastructure as a Service (IaaS)

Even if service models of cloud technologies have been well represented for a decade, the initial steps were rather small. Because before models like Infrastructure as a Service or Platform as a

Service markets became lucrative, initially it was only software as a service applications that achieved significant sales (see Fig. 1).

Fig. 1: Sales of cloud technologies by segment (source: Lindner et al. 2020)

SaaS, PaaS and IaaS in comparison

In the following I would like to compare the various service models with one another for a better overview (see Fig. 2).

Fig. 2: Service models of cloud technologies (source: Lindner et al. 2020)


The first service model with the abbreviation SaaS stands for the term Software as a service and is one of the best-known variants among most end users. Cloud providers provide their customers with software that can be used over the Internet for a fixed monthly price. While the provider monitors and organizes all of the requirements relating to updates and settings, the user has only limited influence on the software itself. The main advantage here is the comparatively low costs and the ability to use the software at any time and from anywhere.

Examples of SaaS: Microsoft Office 365,, GitHub, ownCloud online and Mailchimp


PaaS describes the second service model and stands for the term Platform as a Service . As the name suggests, in return for a payment, the user can gain access to a fully configured and flexibly expandable software environment. There he can also run his own software. PaaS is therefore particularly well represented among software developers who use the service model, for example, to develop their own software applications or to test them in the provided environment. Compared to your own software environment, the flexibility of PaaS is significantly higher and gives software developers the option of different programming languages and almost infinite computing power.

Examples of PaaS: Microsoft Azure, Amazon Web Services and OpenShift


Infrastructure as a Service or short IaaS includes the last service model. It describes a virtual data center and the first alternative to buying your own hardware, such as virtual computers, storage and networks. Since the end user is responsible for the virtualization of the environment and the installation of software, Iaas scores with the advantages of high flexibility and scalability as well as an almost limitless use of IT resources.

Examples for IaaS: Clouds from Google, Amazon and Microsoft

Delivery models of cloud technologies

In addition to the service models, there are also delivery models in the area of cloud technologies. Such a model describes how an acquired service model (SaaS, PaaS or IaaS) can be provided or made available as a service. A distinction is usually made here between three different delivery models

  • Public cloud
  • Private cloud
  • Mixed forms (e.g. hybrid cloud)

The first two are usually more important and widespread in companies (see Fig. 3).

Fig. 3: Use of private and public clouds (source: Lindner et al. 2020)

Public cloud

In practice, the public cloud of any provider is described as a public cloud, such as SaaS applications such as Google Docs or Microsoft Office 365 or IaaS solutions through the clouds from Google, Amazon or Microsoft. The great advantage of the public cloud lies in the possibility of individual and needs-based setup. At the same time, however, in some countries public access can also lead to problems with the legal situation in terms of data protection.

Private cloud

The private cloud, on the other hand, describes a delivery model where data protection obstacles and IT security usually do not pose any problems. The reason for this is that the private cloud is only explicitly available for companies that operate this cloud themselves and make it available to their workforce in the form of company-specific software, a platform or an intranet.

Hybrid cloud

However, since many companies are looking for a combination of the advantages of both cloud technologies, the delivery model of the hybrid cloud has now also established itself. It describes a hybrid form of public and private cloud as well as the possibility of operating certain services with public providers via the Internet and data protection-critical applications and data in their own cloud.

Example of the use of a hybrid cloud

A company stores customer and strategy data in its own cloud. In addition, the company bought its own servers, which are managed by internal IT staff. Since the acquisition of your own servers is very expensive and therefore only limited capacities are available, data that is not worth protecting (e.g. brochures, company presentations …) is stored in the inexpensive public cloud of a regional German provider. A community cloud are infrastructures that are used by several companies, e.g. B. suppliers, for example in the context of a project are operated jointly, with certain services being shared. For example, three suppliers can share IT infrastructure and specialists for the implementation of a project for the same end customer. Only shared data is then stored in the cloud.


The term “cloud” describes the interaction of several services via the Internet, which are divided up into individual task packages so that a different server can always step in in the event of a failure. Although the cloud user never has a precise overview of where their data and applications are currently located in the cloud, they can be sure of their occurrence at all times.

Within the cloud technologies, a distinction is made between service and delivery models and their individual classes.

Service models are split into three different categories so that the cloud user can use different types of abstraction:

  • Software as a Service (SaaS),
  • Platform as a Service (PaaS) and
  • Infrastructure as a Service (IaaS)

On the other hand, cloud providers offer their users three different delivery models:

  • Public cloud
  • Private cloud
  • Mixed forms (e.g. hybrid cloud)

Tip: Read my new book: The way to the cloud at Springer Gabler or book me for a talk .


Lindner, D., Niebler, P., & Wenzel, M. (2020). The way to the cloud – a guide for entrepreneurs and decision-makers . Heidelberg: Springer Gabler.


I blog about the influence of digitalization on our working world. For this purpose, I provide content from science in a practical way and show helpful tips from my everyday professional life. I am an executive in an SME and I wrote my doctoral thesis at the University of Erlangen-Nuremberg at the Chair of IT Management.

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