When you create an application and run it in Windows Azure, the configuration file along with the code that constitutes the package together is called a Windows Azure cloud service. With a cloud service, you can host a multi-tier application in a single host and combine one or more cloud services together with the Web role and/or worker roles, each with its own application files and configurations with the support of autoscaling. A cloud infrastructure maintains the services for you by maintaining virtual copies of the software, patching operating systems and attempting to recover hardware failures. A cloud service is recommended to have at least two instances running to qualify Windows Azure Level Agreement that states 99.95 percent guaranteed connectivity.

Cloud service roles that constitute application and configuration files are of two types: