The main strength of XML is that it separates the content from the formatting. XML tags define what kind of information is present, but not what the computer software should do with it. With XML documents, you can
create multiple style sheets so that one XML document can be turned into different-looking outputs for different audiences
make formatting changes in the style sheet instead of the XML document. For example, if all your headings are 12 points and you want them to be 16 points, in HTML you would have to change each heading's <font> tag attributes. With XML, you would only have to make that change once, in the style sheet.
exchange data between different computer software and platforms, provided that the XML documents are standardized to a particular Document Type Definition (more about this later)