What is a public cloud

The rise and adoption of public cloud services is one of the most important shifts in the history of enterprise computing. A public cloud is a type of cloud computing in which a third-party service provider makes computing resources which can include anything from ready-to-use software applications, to individual virtual machines (VMs), to complete enterprise-grade infrastructures and development platforms available to users over the public Internet. These resources might be accessible for free, or access might be sold according to subscription-based or pay-per-usage pricing models.   The public cloud provider owns and administers the data centers where customers’ workloads run. Service providers assume responsibility for all hardware and infrastructure maintenance and provides high-bandwidth network connectivity to ensure rapid access to applications and data. The cloud provider also manages the underlying virtualization software. In its simplest form, the public cloud model is the computing version of the “utility” model we all use when consuming electricity or water in our homes.  


Public cloud services

A broad array of public cloud computing services are available today, comprising multiple offerings and service models. Almost any service that doesn’t require physical proximity to the hardware that’s hosting it can now be delivered via the cloud.



Infrastructure-as-a-Service (IaaS): In IaaS, the public cloud provider offers access to fundamental compute, network, and storage resources on demand over the public Internet or through dedicated connections. This might consist of direct access to the underlying hardware—a model known as bare metal but more commonly, it’s access to already virtualized resources. 





Platform-as-a-Service (PaaS): PaaS provides application developers a complete platform including all necessary hardware, software, and infrastructure upon which applications can be built, run, and managed. The entire platform infrastructure is typically managed by the cloud provider, and users need not worry about lower-level details.  





Software-as-a-Service (SaaS): With SaaS, users receive access to cloud-hosted software applications. Instead of being installed on local devices, these applications reside in the cloud and are accessed through a web browser or via an API.

Other service models (which are often more specialized) are also available. These include offerings like Business-Process-as-a-Service (BPaaS), in which an entire horizontal or vertical business process is delivered together as a combination of related IaaS, PaaS, and SaaS services; or Function-as-a-Service (FaaS), a subset of SaaS in which application code runs only in response to specific events or requests. The vast majority of these offerings, however, are subtypes or extensions of the three basic cloud computing service models.


Public cloud, private cloud, and hybrid cloud


Hybrid cloud integrates private and public clouds, using technologies and management tools that allow an enterprise to move workloads seamlessly between both as needed for optimal performance, security, compliance, and cost-effectiveness.

For example, hybrid cloud enables a company to keep sensitive data and mission critical legacy applications (which can’t easily be migrated to the cloud) on-premises while leveraging public cloud for SaaS applications, PaaS for rapid deployment of new applications, and IaaS for additional storage or compute capacity on demand.

The majority of enterprise cloud adopters turn to hybrid cloud architectures so that they have the flexibility to choose the best cloud environment (public or private) for each of their workloads or move the workloads between clouds as their needs change.

For more background on hybrid cloud, see our video “Hybrid Cloud Explained”:


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