In Public cloud the computing infrastructure is hosted by the cloud vendor at the vendor’s premises. The customer has no visibility and control over where the computing infrastructure is hosted. The computing infrastructure is shared between any organizations (sharing the infrastructure).
The computing infrastructure is dedicated to a particular organization and not shared with other organizations. Some experts consider that private clouds are not real examples of cloud computing. Private clouds are more expensive and more secure when compared to public clouds.
Private clouds are of two types:
- On-premise private clouds and externally hosted private clouds.
- Externally hosted private clouds are also exclusively used by one organization, but are hosted by a third party specializing in cloud infrastructure. Externally hosted private clouds are cheaper than On-premise private clouds.
Organizations may host critical applications on private clouds and applications with relatively less security concerns on the public cloud. The usage of both private and public clouds together is called hybrid cloud. A related term is Cloud Bursting. In Cloud bursting organization use their own computing infrastructure for normal usage, but access the cloud for high/peak load requirements. This ensures that a sudden increase in computing requirement is handled gracefully.