Web services are self-contained functions that can be published and invoked across the Web using XML-based protocols. Amazon Web Services (AWS) offers applications that range from retrieving information about a set of products to adding an item to a shopping cart to checking on the status of a transaction. You can access Amazon Web Services through a REST (also called "XML over HTTP" or "XML/HTTP") or a SOAP interface. Both of these methods return structured data (product name, manufacturer, price, etc.) about top-selling products at Amazon.com (US), Amazon.co.uk (United Kingdom), Amazon.de (Germany), or Amazon.co.jp (Japan) based on parameters such as keyword search terms and browse nodes.