HTML5 has a new time element. You can use it simply to identify parts of your document that describe a date/time, but the most useful part is you can use it to describe a date/time in a machine readable format using the datetime attribute. For example

<time datetime="2011-11-12T14:54">Nov 12, 2011 at 2:54 PM</time>

You can write the date time in any format, even translate it, but still make the date/time accessible to machines.

Many Joomla-based sites, including this one, include date/time information for articles, but in most cases, don’t use the HTML5 time element.

Note Since the time element is not part of HTML4, You should only tag content with the time element if your template is generating HTML5. You can check that be inspecting the DOCTYPE (the first line if you view your site’s source). An HTML5 doctype look’s like <!DOCTYPE html>.

In order to markup your documents with the time element, you first need to find where your template inserts dates. In most templates I’ve seen, this is somewhere in <templatename>\html\com_content. Good places to start include (a good template might have one location, but I’ve never seen that in while, except for this site):

  1. <templatename>\html\com_content\article\default.php
  2. <templatename>\html\com_content\category\blog_item.php

Within those files, search for item->created, item->modified, and item->publish_up. Here, the details will really depend on the template, but one common thing is you’ll need to format the date/time into the format expected by HTML5. To do that, use the DATE_W3C constant, for example.

<?php echo JHtml::_('date', $this->item->created, JText::_(DATE_W3C)); ?>

That gets inserted as the datetime attribute. For this site, the entire code is

<time class="create article-info-item" datetime="">
<?php  $createdate = JHtml::_('date', $this->item->created, JText::_('DATE_FORMAT_LC')); ?>
<?php  $createdate = '<span itemprop="dateCreated">' . $createdate . '</span>'; ?>
<?php echo JText::sprintf('COM_CONTENT_CREATED_DATE_ON', createdate); ?>
</time>

The code for the other date/time values is very similar.