Question: What does an XML document actually look like (inside)?

Answer: The basic structure of XML is similar to other applications of SGML, including HTML. The basic components can be seen in the following examples.
An XML document starts with a Prolog:
1. The XML Declaration

which specifies that this is an XML document;
2. Optionally a Document Type Declaration

which identifies the type of document and says where the Document Type Description (DTD) is stored;
The Prolog is followed by the document instance:
1. A root element, which is the outermost (top level) element (start-tag plus end-tag) which encloses everything else: in the examples below the root elements are conversation and titlepage;
2. A structured mix of descriptive or prescriptive elements enclosing the character data content (text), and optionally any attributes (?name=value? pairs) inside some start-tags. XML documents can be very simple, with straightforward nested markup of your own design.