XML, the metalanguage that is used for defining data elements on a Web page and business-to-business documents, is continuing to boom. Its now six years since the introduction of the XML spec, and now its spawned hundreds of child languages (or schemas), for use in all kinds of modern computing applications.
This boom in XML schemas is pretty strong indication to some that the XML spec has been an out and out success. Others, however, feel that the large number of spawned schemas has the potential to create the kinds of problems that XML was designed to deal with. Nevertheless, as a data exchange format, XML is hard to beat, and is "a must for companies wishing to join the growing movement toward building new business software using a more flexible model called a services-oriented architecture."