This document summarizes key aspects of XML including: - XML is a text-based format for describing data structures that is both human and machine readable. - XML became a W3C standard in 1998 and is commonly used for exchanging data between disparate systems. - Java can be used to generate, access, format, parse, validate, and transform XML data. - XML documents have a root element containing other nested elements and attributes to describe hierarchical data. - Well-formed XML documents follow syntax rules for proper nesting of start/end tags and quotes around attribute values. - XML parsers like SAX and DOM are used to read XML documents sequentially or build a navigable tree structure in memory