The document provides an overview of XML (eXtensible Markup Language). It discusses the need for separating presentation from content that XML addresses. XML allows for structuring and adding semantic meaning to data. It also describes the main components of an XML document including the prolog, elements, attributes, entities, and DTD (document type definition). The DTD outlines rules for the document and enables validation. The document then explains various XML features in more detail such as content models, attribute declarations and types, internal/external DTDs, and entities. It concludes with an overview of the Together Control Center XML editor functionality.