Step 6 of 8.1.2.1 Start tags of the HTML5 spec says that void elements may have a single / character. I think this is so it\'s easier to migrate sites
/
This article explains the difference between the two versions: http://www.colorglare.com/2014/02/03/to-close-or-not-to-close.html
The two versions are completely identical.
Actually, one might argue that adding "/` to a void tag is an ignored syntax error.