With XML You Invent Your Own Tags
The tags in the example above (like and ) are not defined in any XML standard. These tags are "invented" by the author of the XML document.
That is because the XML language has no predefined tags.
The tags used in HTML are predefined. HTML documents can only use tags defined in the HTML standard (like , , etc.).
XML allows the author to define his/her own tags and his/her own document structure.