• A private cloud is a particular model of cloud computing that involves a distinct and secure cloud based environment in which only the specified client can operate.
• The Private Cloud allows systems and services to be accessible within an organization. The Private Cloud is operated only within a single organization. However, it may be managed internally or by third-party.
• As with other cloud models, private clouds will provide computing power as a service within a virtualized environment using an underlying pool of physical computing resource. However, under the private cloud model, the cloud (the pool of resource) is only accessible by a single organization providing that organization with greater control and privacy.
• Traits that characterize private clouds include the ring-fencing of a cloud for the sole use of one organization and higher levels of network security.
• Private cloud services draw their resource from a distinct pool of physical computers but these may be hosted internally or externally and may be accessed across private leased lines or secure encrypted connections via public networks.
• The private cloud model is closer to the more traditional model of individual local access networks (LANs) used in the past by enterprise but with the added advantages of virtualization.
• The additional security offered by the ring-fenced cloud model is ideal for any organization, including an enterprise that needs to store and process private data or carry out sensitive tasks.

Features and Benefits of Private Cloud:

Cost and Energy efficient: Private cloud resources are not efficient as a public cloud but they offer more efficiency than public cloud as they minimize the investment into unused capacity.

Higher security and Privacy: Private cloud operations are not available to general public and resources are shared from a distinct pool of resources, therefore, ensures high security and privacy.
More control: Private cloud has more control on its resources and hardware than public cloud because it is accessed on within an organization.

Cloud Busting: This service allows the provider to switch certain non-sensitive functions to a public cloud to free up more space in the private cloud for the sensitive functions that require it. Private clouds can even be integrated with public cloud services to form hybrid clouds where non-sensitive functions are always allocated to the public cloud to maximize the efficiencies on offer.

Improved reliability: Even where resources (servers, networks etc.) are hosted internally, the creation of virtualized operating environments means that the network is more resilient to individual failures across the physical infrastructure.

Drawbacks: 

Limited Scalability: Private cloud can be scaled only within the capacity of internal hosted resources.

Restricted area: Private cloud is only accessible locally and is very difficult to deploy globally.

Inflexible pricing: In order to fulfill demand, purchasing new hardware is very costly.

Additional skills: In order to maintain cloud deployment, the organization requires more skill and expertise.