Cloud computing is a combination of multiple skills. Those are cloud services and Virtual machines. These two are two different concepts. Cloud computing is a service provided to users. The VM - virtual machines are the concept of virtualization.
Public Vs Private Vs Hybrid Cloud
- Public Cloud: The cloud which is available to the public is called the PUBLIC cloud.
- Private Cloud: The cloud which is available to the particular Business/Company is called PRIVATE Cloud.
- Hybrid Cloud: A private cloud is maintained all the resources that needed, in case of emergency, it takes resources from the PUBLIC cloud.
- Cloud services (remote data and computation) are exposed as simple and user-friendly web services. For example, Microsoft's ADO.NET (originally called Astoria) provides the tools to expose any data object from a collection, stored in a database or other form, as a URI to an encoded form using a standard such as JSON or ATOM representation
- Google's AppEngine provides a way to deploy a remote Python script that becomes a web service that can access data in their BigTable database system.
- To deliver highly available and flexible services (i.e., computation as a service), and owing to the maturity of virtualization technology, Virtual Machines (VMs) are used as a standard for object deployment in the cloud.
- VMs decouple the computing infrastructure from the physical infrastructure. VMs allow the customization of the platform to suit the needs of the end-user.
- For example, in the Amazon Elastic Compute Cloud (EC2), the customer selects his/her preferred VM image (virtual appliance) from a list of various versions of Linux and Windows servers