A new Amazon.com Web Services facility makes it possible for developers to "build applications and tools that will allow them to incorporate many of the unique features of Amazon.com into their web sites free of charge. Among its many features, Amazon.com's Web Services will allow third party sites to search and display products from Amazon.com's web site, and enable visitors to those sites to add items to their Amazon.com shopping carts. Developers can access AWS through two industry standards: XML and SOAP." The toolkit allows one to search for Amazon.com products in a variety of ways (keyword, author, actor, director, ASIN, UPC, publisher, etc) and to get results in XML, including customer reviews and product similarities. One can pass the server a URL that references a style sheet along with the SOAP or XML request, and receive the XML data rendered with the nominated style sheet. The developer's toolkit includes documentation on how to make calls to Amazon.com Web Services, a DTD and XSD specification, the SOAP WSDL file, an example XSLT style sheet, examples of 'lite and 'heavy' XML results documents, sample SOAP requests, and the Amazon.com Web Services license.

From the FAQ:

XML over HTTP uses URIs with specific name/value pairs to invoke methods and processes within Amazon.com's Web Services framework. The URI is the primary method used for message passing. Once the URI is processed, a well-formatted XML document is returned as a response. Because XML/HTTP is based on such a widely accepted methodology, most developers should have no problem creating applications capable of quickly communicating with the Web services that expose this interface.

SOAP (Simple Object Access Protocol), a more complex method of sharing messages between client and server, was developed to deal with the limitations of XML/HTTP. SOAP is a lightweight protocol intended for exchanging structured information in a decentralized, distributed environment. It uses XML technologies to define an extensible messaging framework providing a message construct that can be exchanged over a variety of underlying protocols. The framework has been designed to be independent of any particular programming model and other implementation-specific semantics.

From the announcement 2002-07-16: "On July 16, 2002 Amazon.com "launched its first version of 'Amazon.com Web Services,' a platform for creating innovative Web solutions and services designed specifically for developers and web site owners. By using Amazon.com Web Services, developers can build applications and tools that will allow them to incorporate many of the unique features of Amazon.com into their web sites -- free of charge... Among its many features, Amazon.com's Web Services will allow third party sites to search and display products from Amazon.com's web site, and enable visitors to those sites to add items to their Amazon.com shopping carts. Developers can access AWS through two industry standards: XML and SOAP (Simple Object Access Protocol)... Amazon.com Web Services is available free of charge. It is also integrated with the Amazon.com Associates Program, which allows web sites to earn referral fees from purchases made at Amazon.com via links on their web sites. The powerful combination of Amazon.com Web Services and the Associates Program will allow developers to incorporate more Amazon.com features onto their web sites, ultimately driving more traffic and more referral fees as a result..." See "Amazon.com Launches Web Services. Developers Can Now Incorporate Amazon.com Content and Features into Their Own Web Sites. Extends 'Welcome Mat' for Developers."