What is a cloud? What is cloud computing?

The terms cloud and cloud computing are used very often, but what is actually behind it? In this article we explain the different terms in an understandable way.

The term cloud has established itself as a short form of cloud computing .

Briefly summarized: The term cloud means the interaction of several servers. The servers take on tasks such as data storage or complicated program sequences. The cloud user does not notice how many servers are behind the cloud.

Even if one server fails, it has no impact on the entire system. This independence from the individual servers is therefore referred to as cloud, since the user does not have to have an overview of the individual units (cloudy / unclear for the user). The cloud is the big picture of these computing units.

Cloud / cloud does not mean that your data is only transmitted via “clouds” or satellites. Everything essentially takes place on Earth and your “normal” internet connection via radio towers, routers, cables and data centers is used.

Important basics

Running your own software in the cloud is also an option. The different models: Infrastructure as a Service, Platform as a Service and Software as a Service are explained in more detail below in Cloud AZ.

Thanks to cloud services, we can access much larger amounts of storage. We can access our data in the cloud from anywhere in the world. We can run more complex software than ever before. And we can network our devices better.

Of course, all this also involves dangers . With the right access data, others can also access our cloud, be it secret services, other government agencies or companies with immense market power. Therefore, we present offers on this page that promise a secure (re) cloud .

Another disadvantage of the cloud should not be forgotten: without the Internet, there is no cloud. Even though we have access to the Internet from more and more places these days, you should always keep in mind that your data is stored on a different storage medium, which you can often only access via the Internet.

Cloud A-Z

There are many other terms related to the cloud that keep coming up in connection with cloud and cloud computing. These terms are explained in Cloud AZ.

Business Cloud: This term is used by this website to identify offers that are aimed at companies.

Cloud computing: see above, means the interaction of several servers that take on tasks as a whole and can provide storage space, for example.

Community Cloud: means the cloud as a (local) community project. A user group gets together and shares the costs for the project. For example, a community cloud from several universities or colleges is conceivable.

Hybrid cloud: A combination of the private cloud and public cloud, depending on individual needs.

Infrastructure as a Service (IaaS): In contrast to PaaS and SaaS, IaaS takes effect at the lowest level, the hardware compilation. This cloud service provides you with servers that you yourself divide into your own virtual computer clusters , i.e. computer networks. You are responsible for the selection of any software.

Multi Cloud: Based on the idea of the hybrid cloud, several cloud offers are linked and bundled here.

Network Attached Storage (NAS): Any cloud software offers more than just storage and therefore goes beyond a NAS. However, if, for example, your own hard drive is made available via the router in the network, this is referred to as NAS storage space that is available via the network.

NIST (National Institute of Standards and Technology, USA): The US institute developed a definition of the cloud . More details can be found in the next section on this page.

Platform as a Service (PaaS): PaaS acts between IaaS and SaaS on the 2nd level. You will have access to a completely set up software environment in which you can also run your own software, for example.

Private cloud: own computer structure or own cloud. This can be an in-house cloud or the small cloud server in your living room.

Public cloud: IT infrastructures or a cloud that is publicly accessible. On our site, we also refer to providers as so-called cloud hosters.

Software as a Service (SaaS): is also referred to as software on demand. You can use selected software that runs on the servers in the cloud. You have only limited influence over the software. Some web applications, such as an online office offering, can already be referred to as SaaS.

Virtual private cloud: A public cloud is accessed via a local (virtual) environment. The protection is usually done by a VPN.

Definition of Cloud Computing

Luckily, there is even a definition of cloud computing made by the US institute NIST. This definition has not only shaped our Cloud AZ with terms like Multi Cloud & Co., but also includes some criteria.

5 characteristics are mentioned that are cloud-specific:

1. Use on demand (“On-demand self-service”): The user can access cloud capacities at any time without human intervention. 
2. Access using known technologies (“Broad network access”): Users can access the cloud via their Internet connection and corresponding clients. This means that devices such as your own computer, but also smartphones and tablets can be used to access the cloud. 
3. Pooling of resources (“Resource pooling”): The server capacities are bundled and present themselves to the user as a cloud without him being able to identify individual servers. 
4. Resource adjustment (“Rapid elasticity”): The resources that are available to the individual user can be adjusted – possibly even automatically. This gives the user the impression of unlimited storage space. 
5. Monitoring of the service (“Measured service”): This does not mean the monitoring of the data itself. The individual servers within the cloud are automatically monitored and optimized.

If you apply these criteria yourself to a cloud service you are familiar with, you will notice what everything a cloud can be and how far the concept of the cloud is.

What is a public cloud?

In a public cloud, abstract IT infrastructures are accessible via the public Internet. Services such as computing power, storage space, infrastructures or applications are available. Own investments in hardware and software are superfluous due to the public cloud.

In contrast to a private cloud , the public cloud makes its services available not only to individual organizations, but to a large number of users via the public Internet. Customers can rent services such as computing power, infrastructure, storage space or applications from a public cloud service provider. There are various models for billing services. The models have in common that the user usually pays for the service actually provided, depending on usage. There are also subscription models or free  advertising-financed public cloud services. The advantage of using the public cloud is that there is no need to install and operate your own IT infrastructure and software. High investment costs can be avoided. If necessary, it is possible to flexibly expand the services used. IT resources can be combined according to requirements and adapt to the current need for computing power or storage space. Examples of public cloud offerings are Microsoft Azure or Amazon’s Elastic Compute Cloud (EC2).

Possible services of a public cloud

Cloud services, such as those made available in a public cloud , can include different types of services. Possible cloud services are:

• Software as a Service, abbreviated SaaS
• Platform as a Service, abbreviated PaaS
• Infrastructure as a Service, abgekürzt IaaS

Infrastructure as a Service ( IaaS ) offers users virtualized computer hardware resources. These include virtual machines, networks or storage. With IaaS, users can put together their own IT infrastructure and run any software on it. The user is responsible for the installation and operation of the software. With Platform as a Service ( PaaS ), the service provider provides customers with runtime and programming environments whose computing and data capacities can be flexibly adapted. On a PaaS environment, applications can be developed or operated within the environment provided by the service provider. Software as a Service ( SaaS) provides direct access to applications or specific software. The cloud provider is responsible for operating the software. The user only uses the software. The various cloud services are not limited to the public cloud, but are also available in other cloud models. In addition to the public cloud, there are the private cloud, the hybrid cloud and the community cloud.

Essential characteristics of a public cloud

To describe a cloud environment as a public cloud, it has to meet various criteria. Access to the cloud should be possible for a large number of users via public network structures and the Internet. The resources are to be made available to users as required and should be able to adapt flexibly to changing requirements. The cloud services are characterized by their good and fast scalability. The services are billed based on usage. Customers only pay for the services provided by the provider that they actually use. For this, it is necessary that the use of computing power, bandwidth, storage space or applications is measurable for the provider and customer.

Ideally, users can book or cancel services directly and pay online. You are not bound by long-term contracts. Self-service interfaces for customers are available for booking and adapting the required services. It is particularly important in a public cloud that the shared resources of different customers are hermetically shielded and separated from one another. Customer-specific data must not be available across the board and must be protected against unauthorized access. At the same time, the service provider must ensure that neither the availability nor the performance of the individual environments influence each other.

In order to save hardware resources and not to use dedicated hardware for every customer, the providers usually use virtualized environments. They are a distinguishing feature of cloud services. Virtualized environments ensure better utilization of data center resources while reducing hardware costs . The separation of customer environments can not only be realized through virtualization. In some cases, there is also a separation on a hardware or application basis.

Advantages of a public cloud

Public Cloud Services users benefit from numerous advantages compared to conventional, dedicated IT structures. The installation and setup of the services is simple and inexpensive. High investment costs are avoided because the hardware and infrastructure are operated by the service provider. All services can be flexibly scaled depending on current or future needs. At the same time, users do not have to pay for unused resources, since the billing models only charge for services that are actually used. Changes to the services can be implemented quickly without lengthy hardware purchases and installations. It is possible to react quickly even to short-term peak loads.

Since the provider operates its services in professional data center environments and provides appropriate backup solutions, the services generally offer higher availability than can be achieved in your own IT environment. The user does not have to have resources for maintenance or possible troubleshooting and can concentrate on his actual core business. The providers implement modern security concepts in their cloud environments and increase the security of the services provided. Cloud systems are usually managed around the clock and are monitored by security professionals.

Differentiation of the public cloud from the private cloud

The public cloud differs from the private cloud in that the services offered are available to the general public and not exclusively for individual organizations. A private cloud is either operated by the organization itself or provided exclusively by a service provider only for this organization.

The use of a public cloud can become obsolete due to strict legal data protection regulations or security concerns. In certain industries, regulation prohibits the transfer of data to external service providers who do not meet the strict German or European data protection requirements. In such cases, a private cloud or a hybrid form of private and public cloud, the hybrid cloud , must be used. It offers combined access to services of a public cloud and a private cloud depending on the requirements of the respective application. Compared to the public cloud, the private cloud has the advantage that the performance of the services is not influenced by other customers.

What is a private cloud?

The private cloud provides its services exclusively for organizations. In contrast to the public cloud, it cannot be reached by the general public via the Internet. The private cloud can be hosted on the company’s own computers or by third parties and offers a high degree of control and security.

A private cloud environment promises a high degree of control and security : In contrast to the public cloud , the private cloud is not accessible to the general public via the Internet. It is operated exclusively for individual organizations such as companies or authorities. Depending on the version, it can be hosted on your own computers or on servers from external providers. The cloud services are accessed either via the delimited intranet or via a closed virtual private network (VPN).

A private cloud is an internal, organization-related cloud that only makes its applications available to authorized users. Access can be secured, for example, by firewalls. Other names for the private cloud are corporate cloud or company cloud. The private cloud acts as an internal service provider for users . Like the public cloud, the private cloud relies on virtualization and distributed computing.

Since this form of cloud computing does not have to be shared with other users, it offers a high degree of security, control and flexibility. The applications can be scaled according to the individual requirements of the organization and can be used very efficiently. Computer, storage and network capacities are based on your own needs and are not subject to the restrictions of the public cloud.

The private cloud enables the fast adjustment of computing power and the user-dependent billing of the services used. The private cloud is an ideal solution, especially for organizations that have to meet strict data security and data processing requirements or are subject to government regulation. The special architecture of the cloud services offers considerable savings potential compared to conventional IT infrastructures. In some areas, the private cloud is used together with the public cloud in the form of a so-called hybrid cloud . It combines the advantages of both worlds in its own cloud model .

Virtualization as the basis of the private cloud

The technical basis of the private cloud is virtualization. By using modern virtualization technologies, IT services and resources can be decoupled from physical devices. Applications are no longer operated locally on end devices or servers, but are made available virtually in a cloud environment. The advantage of virtualization is that resources can be flexibly allocated to the various applications. It also increases availability because the failure of individual computers can usually be compensated for by the virtualized environment.

Users access the applications via the internal network or specially secured public network structures (keyword VPN). Each user receives the rights they need for this. He has to authenticate himself to the cloud services. Compared to conventional IT infrastructures, the cloud eliminates the need to operate separate servers for individual applications. A virtualized server environment is available for all services.

The four different types of private cloud

The private cloud can in turn be divided into four different sub-types. These types are:

• die interne Private Cloud
• the managed private cloud
• the hosted private cloud
• die Community Private Cloud

With the internal private cloud, the company or organization itself operates the IT infrastructure for their services. The infrastructure for the cloud is also internally hosted for the managed private cloud, but is managed, maintained and monitored by an external provider. The hosted private cloud is housed in an external data center from a provider of cloud services. This operates the cloud separately from other environments on behalf of the organization and only makes the applications available to the users of the organization. The community private cloud is a special form of private cloud, in which several companies, for example from the same industry or from the extended group of companies, access a common cloud. It is basically an industry-specific private cloud.

Advantages of the private cloud

Private cloud users benefit from the many advantages of cloud computing without having to hand over control of their data and IT infrastructure to an external provider. Compared to conventional structures, the entire IT can be streamlined and operated more efficiently and cost-effectively. The server environment is consolidated through the virtualization and decoupling of specific hardware.

The resources are bundled in a central and at the same time flexible pool. Capacities are needs-based and scalable almost in real time. The private cloud offers further advantages over a public cloud. The performance and bandwidth of the cloud are exclusively available to users. No restrictions due to the simultaneous use of third parties are expected. The protected, separate operation of the private cloud minimizes security risks for the organization. If special security measures have to be taken, this is easy and application-specific. The interests of third parties are not to be taken into account.

Delimitation of the internal private cloud from the public cloud and security aspects

There is no difference in terms of the technical basis of the public and private clouds. However, the private cloud is not public and is operated and managed separately. Only authorized users have access to applications and data. The organization remains in full control of their data at all times. Due to special data protection requirements, the use of a public cloud may be prohibited.

The internal private cloud is clearly differentiated from the cloud structures, such as those offered by Amazon or Microsoft. In the public cloud, customers have to share the virtualized infrastructure. In addition, in many cases it is not possible to determine where the data is hosted. If this happens in data centers outside of Germany or Europe, certain compliance or regulatory requirements may no longer be adhered to. Customers lose influence on the location and the type of data storage. At the same time, they can protect data- and only partially determine safety aspects. Specified offer packages from the public cloud providers can further restrict the availability, performance and security of the services.

What is a hybrid cloud?