The document discusses processing XML documents using the DOM (Document Object Model). It describes the DOM as a standard for accessing and manipulating XML and HTML documents. The DOM defines objects and properties for all document elements and methods for interacting with them. It represents an XML document as a series of nested nodes in a hierarchical tree structure. When an XML processor parses a document, it builds a DOM representation in memory that provides a standardized way to navigate, search, and modify the document programmatically. The chapter discusses different types of DOM nodes and relationships, as well as how various XML processors work with DOM trees.