Comment by mark_and_sweep

> Is there still a real-world use case for XHTML

If I need the markup of a page to not contain any structural errors, I often use XHTML for testing at least because, though it's a little more verbose, if there's a nesting error, for example, the browser will flat out refuse to render it and show some sort of stacktrace error page instead. So it's quite a good built-in "tool" for checking that your markup is clean.

With HTML, everything goes and the browser will happily render broken markup, which is probably the correct default for the web as a whole. After all, you surely don't want a page like Wikipedia to show an error message to its users because a developer forgot to close a tag somewhere.