The Windows® Azure™ Platform is an internet-scale cloud computing and services platform hosted in Microsoft data centers. The Windows Azure Platform provides a range of functionality to build applications that span from consumer web to enterprise scenarios and includes a cloud operating system and a set of developer services. Fully interoperable through the support of industry standards and web protocols such as REST and SOAP, you can use the Azure services individually or together, either to build new applications or to extend existing ones.
http://www.microsoft.com/azure/services.mspx