Introduction to XML

XML files employ a format in which data is contained in a nested, hierarchical structure of tags which give context and meaning to the data contained between and within the tags. It has been described as similar to HTML because both in XML and in HTML the tags used can each have attributes, can surround data value elements (in HTML these are mostly text strings to be displayed), and can support deeper nesting of tag structures.

Where tags surround data or a deeper structure, they have opening tags balanced with closing tags, those nested inner tags always being closed before outer tags as in this snippet of HTML:

<b>This text will be displayed as bold <i>and this as bold italics</i></b>.

Where a tag has attributes, but doesn't surround any data or other elements, the opening and closing tags can be combined into one, with a closing "slash-bracket":

<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />

However, a big distinction...