Public cloud is a platform that uses the standard cloud computing model to make resources such as virtual machines, applications or storage, available to users remotely. In short it is a type of computing in which a service provider makes resources available to the public via the internet. Public cloud services may be free or offered through a variety of subscription or on demand pricing schemes, including a pay-per-usage model.

A public cloud is a fully virtualized environment. In addition, providers have a multi-tenant architecture that enables users or tenants to share computing resources. Each tenant’s data in the public cloud, however, remains isolated from other tenants. Public cloud also relies on high-bandwidth network connectivity to rapidly transmit data. Public cloud architecture can be further categorized by service model. Common service models include SaaS, IaaS and PaaS.

In general, the public cloud is seen as a way for enterprises to scale IT resources on demand, without having to maintain as many infrastructure components, applications or development resources in-house. The pay-per-usage pricing structure offered by most public cloud providers is also seen by some enterprises as an attractive and more flexible financial model. For example, organizations account for their public cloud service as an operational or variable cost rather than capital or fixed costs. In some cases, this means organizations do not require lengthy reviews or advanced budget planning for public cloud decisions.

Because of the multi-tenant nature of public cloud, security is an ongoing concern for some enterprises. Public cloud providers offer security services and technologies, such as encryption, and identity and access management tools. However, it is the enterprise’s responsibility to implement such offerings and use best practices to protect their data. A shared-responsibility model helps identify which components are the responsibilities of the cloud vendor and which should be secured by the user.