SOAP

To pass structured data across the Web (such as passing objects or calling methods on objects), the sender and receiver must agree on how the data will be transmitted. SOAP (Simple Object Access Protocol) is Microsoft's new protocol used to exchange structured data over the Web using an XML format. SOAP is lightweight (doesn't consume a lot of resources or bandwidth) and makes use of the widely accepted HTTP protocol. SOAP is fundamental to Microsoft's .NET strategy because it allows different applications on multiple platforms to share structured data and interoperate across the Web.