environment. On the other hand, a cloud is hybrid when a company uses public cloud services for tasks such as prototyping or testing a new application. When the application is completed it may be moved to the private cloud. In another situation, the Web servers are on a public cloud service that’s integrated with payment systems that are run in a private cloud. 

A company with a private cloud may choose to combine some public services for capabilities that are commodities with private services based on the ability to deliver fast innovation to their ecosystem. For example, companies are increasingly discovering that it’s practical to pay a per-user, per-year price for customer relationship management (CRM) and leave the day-to-day management to a trusted vendor. But many companies also want to keep control over some of their most sensitive data. Therefore, they may choose to keep data about prospects on a public cloud. However, after those prospects become customers, the companies may begin storing that data on their own premises in their own servers, which is the hybrid cloud model. 

## Core Cloud Capabilities 

Regardless of the model that you use, some core capabilities that are essential in the cloud environment include the areas covered in this section. 

## Elasticity and self-service provisioning 

A key feature of a cloud environment is that it provides a platform that’s designed to be elastic (you can use just the resources you want when you need them), so the users/ customers provision resources, such as computing or storage resources, that they pay for on a per-unit basis. When the user no longer needs that resource and stops paying, the resource is released back into the pool of resources. This helps organizations avoid the cost of idle computing resources. Instead of purchasing, managing, and maintaining a server environment, for example, a business can purchase computing on demand, avoiding capital expenditures. 

