A void element is an element, which can have attributes, but no contents. Based on the current HTML Specification (28 May 2013) these are the void elements:
area, base, br, col, command, embed, hr, img, input, keygen, link, meta, param, source, track, wbr
So we do not have to end those tags anymore. Example:
<meta charset="utf-8">
instead of
<meta charset="utf-8"/> <!--(XHTML doctype)-->
If you also encounter an error on your html files saying “The element type x must be terminated by the matching end-tag x”, you are probably either not using HTML5 as your doctype, or your view resolver does not support HTML5 / its HTML5 mode is not activated.