Example of valid HTML:
<p>This is a paragraph
Equivalent in XHTML:
<p>This is a paragraph</p>
Tags that don’t contain data (like breaks, images, and horizontal rules) should also be closed in HTML. There’s no need to write an opening and closing tag, though. We can use the perfectly acceptable shortcut:
<!— Examples of properly closed XHTML tags -->
<!—Properly closed image -->
<img src=”someimage.gif” alt="An image" />
<!—Properly closed break tag -->
<br />
<!—Properly closed horizontal rule -->
<hr />