What are deployment models in cloud computing?

In my third class of cloud computing we learn about the deployment Models of cloud computing, the cloud is an approach that harnesses the power of servers, as well as virtualization technologies that combine servers into large computing pools and divide single servers into multiple virtual machines. And there are several different deployment models for implementing cloud technology.  

The four primary types of cloud models are:

Public
Private
Hybrid
Community

Private cloud.
The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers . It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off premises.
Community cloud.
 The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns . It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises.
Public cloud.
The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them.  It exists on the premises of the cloud provider.
Hybrid cloud.
The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability.