Cloud Computing is an old model (Utility services) of delivering services, which got hype in the market nowadays and consider as future computing services model.
Cloud Computing refers to both the applications delivered as services over the public Internet and the hardware and systems software in the data centers that provide those services.
There are main three (3) cloud deployment models.
1. Private – It refers to cloud deployment inside the boundaries of an organization by using it’s own IT resources.
The Forrester Research article related to private cloud deployment. Deliver Clouds inside your walls
2. Public – It refers to public internet available for everyone to use those IT services and applications delivered via internet.
3. Hybrid – The mix of both worlds (Private + Public) to deliver the IT services to their internal organization and partners.