Cloud services can be provided at different levels. For example, at the level of applications, platforms or infrastucture.
A wide range of Cloud services are currently available to the public. The following are just a few examples of Cloud applications.
Software-as-a-Service commonly refers to applications delivered to the end user through a web browser or any other web-rich client. Examples include Microsoft OfficeLive, DropBox, and CloudNumbers.
Platform-as-a-Service provides more customisation room, for example, for a developer to acquire a bespoke platform (such as operating system, software, and libraries) that is usually used to carry out a very specific task. Examples include Google AppEngine, SalesForce VMforce, and Joyent Accelerator.
Infrastructure-as-a-Service provides maximum control where a computing infrastructure can be assembled from the operating system upwards. Examples include Amazon EC2, Eucalyptus Community Cloud, and IBM Cloudburst.