Public Cloud: A public cloud is a type of computing in which a service provider makes resources available to the public via the internet. Some public cloud providers offer resources for free, while clients pay for other resources by subscription or a pay-per-usage model.
Public cloud consists of the following key characteristics:
broad network access
on-demand computing and self-service provisioning
pay-per use pricing
resiliency and availability
scalability and rapid elasticity
When selecting a provider, organizations can opt for a large, general-use provider -- such as AWS, Microsoft Azure or Google Cloud Platform (GCP) -- or a smaller provider. General cloud providers offer broad availability and integration options and are desirable for multipurpose cloud needs. Niche providers offer more customization.
These are the three most common service models:
Infrastructure as a service (IaaS), in which a third-party provider hosts infrastructure components, such as servers and storage, as well as a virtualization layer. The IaaS provider offers virtualized computing resources, such as VMs, over the internet or through dedicated connections.
Platform as a service (PaaS), in which a third-party provider delivers hardware and software tools -- usually those needed for application development, including operating systems -- to its users as a service.
Software as a service (SaaS), in which a third-party provider hosts applications and makes them available to customers over the internet.
Private Cloud: A virtual private cloud is an on-demand configurable pool of shared resources allocated within a public cloud environment, providing a certain level of isolation between the different organizations using the resources. A private cloud uses virtualization technology to combine resources sourced from physical hardware into shared pools. This way, the cloud doesn't have to create environments by virtualizing resources one at a time from a bunch of different physical systems.
The Key Benefits of Private Cloud are:
Improved Resource Utilization
Increased Security & Compliance
Once an organization has determined its cloud needs and priorities, it can determine if the private cloud is the right kind of IT environment. For some organizations, the private cloud will be the only realistic option to ensure regulatory compliance. For example, HIPAA requires that electronic protected health information (ePHI) is created, received, stored, and transmitted in a way that ensures its confidentiality, integrity, and availability.
Hybrid Cloud: IT Infrastructure that combines a private cloud with one or more public cloud services, with proprietary software enabling communication between each distinct service. Hybrid cloud services are powerful because they give businesses greater control over their private data.
The Key Benefits of Hybrid Cloud are:
Scalability & Agility
Hybrid cloud computing enables an enterprise to deploy its most sensitive workloads in an on-premises cloud and to host less-critical resources on a third-party public cloud provider. There are two main approaches to hybrid cloud integration: Use the cloud as the front-end application hosting point or create a unified elastic resource pool of data center and cloud functions.