The public cloud is defined as computing services offered by third-party providers over the public Internet. Resources vary by provider but may include storage capabilities, applications or virtual machines.
The main benefits of using a public cloud service are: Easy and inexpensive set-up because hardware, application and bandwidth costs are covered by the provider. Scalability to meet needs. No wasted resources because you pay for what you use. The term "public cloud" arose to differentiate between the standard model and the private cloud, which is a proprietary network or data center that uses cloud computing technologies, such as virtualization. A private cloud is managed by the organization it serves. A third model, the hybrid cloud, is maintained by both internal and external providers. Examples of public clouds include Amazon Elastic Compute Cloud (EC2), IBM's Blue Cloud, Sun Cloud, Google AppEngine and Windows Azure Services Platform.