Document Object Model (DOM) is a description of how an HTML or XML document is represented in an object-oriented fashion. DOM provides an application programming interface to access and modify the content, structure and style of the document.
http://www.w3.org/DOM/
SAX is a serial access parser API for XML. SAX provides a mechanism for reading data from an XML document. It is a popular alternative to the Document Object Model (DOM). The name is acronymically derived from "Simple API for XML".
http://www.saxproject.org/
Java Document Object Model (JDOM) is a Java-based document object model for XML that integrates with Document Object Model (DOM) and Simple API for XML (SAX) and uses parsers to build the document. It was designed specifically for the Java platform so that it can take advantage of its language features. JDOM was developed under the Java Community Process as JSR 102. The name JDOM is a pseudo-acronym.
http://www.jdom.org/
Crimson is a Java XML parser which supports XML 1.0
http://xml.apache.org/crimson/
Xerces is a family of software packages for parsing and manipulating XML, part of the Apache XML project. Xerces (named after the Xerces Blue butterfly) provides world-class XML parsing and generation.
http://xml.apache.org/
The Java API for XML Processing, or JAXP, is one of the Java XML programming APIs. It provides the capability of validating and parsing XML documents. The two basic parsing interfaces are:
the Document Object Model parsing interface or DOM interface
the Simple API for XML parsing interface or SAX interface
http://java.sun.com/webservices/jaxp/
dom4j open source library for working with XML, XPath and XSLT on the Java platform using the Java Collections Framework and with full support for DOM, SAX and JAXP.
http://dom4j.org/