XForms refers to two distinct things:
1. An XML processing language defined by the W3C and described below.
2. An X Window System GUI package, licensed as LGPL. See XForms (toolkit).
XForms is an XML format for the specification of a data processing model for XML data and user interface(s) for the XML data, such as web forms. XForms was designed to be the next generation of HTML / XHTML forms, but is generic enough that it can also be used in a standalone manner or with presentation languages other than XHTML to describe a user interface and a set of common data manipulation tasks.
XForms, much like XHTML 2.0 which is currently under development as of June 2006 and within which XForms will be embedded, differs from previous versions of XHTML. Because of this there is a learning curve for developers, but because XForms in general provides a large time savings for the development of enterprise quality web forms, it can be an attractive alternative for many uses.
XForms 1.0 (Second Edition) has been made an official W3C Recommendation on 14th March 2006. An indispensable list of errata to the 1.0 specification is available, fully incorporated into the main specification as of the Second Edition. XForms 1.1, which introduces a number of improvements, is in progress as a W3C Working Draft as of July 2006