Learn

XML is a markup format for structured data: elements, attributes, and text. Feeds, configuration files, SVG, and office documents are often one long line. Formatting adds line breaks and indentation so you can read the tree.

Well-formed XML is stricter than HTML. Tag names are case-sensitive, every start tag needs an end tag (or the empty-element form <tag />), attribute values must be quoted, and the document has exactly one root element. Five entities are built in: &, <, >, ", and '.

A prefix such as svg in <svg:path> has to be declared with xmlns:svg on that element or an ancestor. xml:lang and xml:space are already declared. xml:space="preserve" tells a formatter to leave the whitespace inside that element alone.