Takes up space without adding any substance. Jokes aside, that space before the / exists as a habit because Internet Explorer couldn't handle tags like <br/>,

Takes up space without adding any substance. Jokes aside, that space before the / exists as a habit because Internet Explorer couldn't handle tags like <br/>, so in order to have valid XML that worked in IE as well you would do <br />. Completely pointless nowadays of course, although I do like the / for single elements. It's kind of nice to be able to write HTML5 and XML both with roughly the same syntax.