Windows Azure provides three core components, Compute, Storage and the Fabric, along with the Fabric controller. Compute is effectively the Windows operating system, this is an instance. These instances contain a copy of your application. Instances also come in two flavours, a Web Role or a Worker Role. Web roles accept and process HTTP requests using IIS. Not everything you may want to run in Windows Azure is a Web application, so Windows Azure also provides Worker roles. A Worker role instance is quite similar to a Web role instance. The key difference is that a Worker role does not have IIS preconfigured to run in each instance. Web and Worker roles can communicate with each other via technologies like WCF, or using Windows Azure Storage queues.