What is public cloud?
A public cloud is a pool of virtual resources—developed from hardware owned and managed by a third-party company—that is automatically provisioned and allocated among multiple clients through a self-service interface. It’s a straightforward way to scale out workloads that experience unexpected demand fluctuations.  (What is public cloud?)

Today’s public clouds aren’t usually deployed as a standalone infrastructure solution, but rather as part of a heterogeneous mix of environments that leads to higher security and performance; lower cost; and a wider availability of infrastructure, services, and applications.

What is public cloud? or What makes a cloud public?

  1. Resource allocation: Tenants outside the provider’s firewall share cloud services and virtual resources that come from the provider’s set of infrastructure, platforms, and software.
  2. Use agreements: Resources are distributed on an as-needed basis, but pay-as-you-go models aren’t necessary components. Some customers—like the handful of research institutions using the Massachusetts Open Cloud—use public clouds at no cost.
  3. Management: At a minimum, the provider maintains the hardware underneath the cloud, supports the network, and manages the virtualization software.

Anybody can provide a public cloud, and there are thousands of providers all over the world. But the Alibaba Cloud, Amazon Web Services (AWS)Google CloudIBM Cloud, and Microsoft Azure are among the largest—and most popular—ones today.


Public clouds are set up the same way as private clouds. Both use a handful of technologies to virtualize resources into shared pools, add a layer of administrative control over everything, and create automated self-service functions. Together, those technologies create a cloud: private if it’s sourced from systems dedicated to and managed by the people using them, public if you provide it as a shared resource to multiple users And the hybrid cloud is a combination of 2 or more interconnected cloud environments—public or private.

All that technology not only has to integrate for the cloud to just work, it also has to integrate with any customer’s existing IT—which is what makes public clouds work well. That connectivity relies on perhaps the most overlooked technology of all: the operating system. The virtualization, management, and automation software that creates clouds all sit on top of the operating system. And the consistency, reliability, and flexibility of the operating system directly determine how strong the connections are between the physical resources, virtual data pools, management software, automation scripts, and customers.

A public cloud is perhaps the simplest of all cloud deployments: A client needing more resources, platforms, or services simply pays a public cloud provider by the hour or byte to have access to what’s needed when it’s needed. Infrastructure, raw processing power, storage, or cloud-based applications are virtualized from hardware owned by the vendor, pooled into data lakes, orchestrated by management and automation software, and transmitted across the internet—or through a dedicated network connection—to the client.

Think about it like this. Cloud computing is the result of a meticulously developed infrastructure, kind of like today’s electric, water, and gas utilities are the result of years of infrastructural development. Cloud computing is made available through network connections in the same way that utilities have been made available through networks of underground pipes.

Homeowners and tenants don’t necessarily own the water the comes from their pipes; don’t oversee operations at the plant generating the electricity that powers their appliances, and don’t determine how the gas that heats their home is acquired. These homeowners and tenants simply make an agreement, use the resources, and pay for what’s used within a certain amount of time.

Public cloud computing is very similar. The clients don’t own the gigabytes of storage of the data they use; don’t manage operations at the server farm where the hardware lives; and don’t determine how their cloud-based platforms, applications, or services are secured or maintained. Public cloud users simply make an agreement, use the resources, and pay for what’s used.

Enterprises are adopting less public- or private-only cloud distributions and more hybrid environment solutions that include bare metal, virtualization, private, and public cloud infrastructure. This allows each environment’s advantage to minimize the disadvantages of another.

For example: Imagine an enterprise running all workloads on 1 virtual cluster. That cluster would be running at full capacity, leading to poor response times and inundation of calls or tickets to operations teams from upset application owners. This situation could be solved by rolling out another virtual cluster and automating the workload balance between the 2. This is the start of a hybrid environment.

The enterprise could expand its infrastructure portfolio to include a private Infrastructure-as-a-Service (IaaS) cloud (like Red Hat® OpenStack® Platform). Workloads that don’t need to run on virtual infrastructure could be migrated to the IaaS private cloud—saving money and increasing workload uptime.

To reduce poor response times to cloud users thousands of miles away, the enterprise could place some workloads on public clouds in nearby regions. This would allow the enterprise to control costs and maintain high availability.