Joomla! Documentation™

The countModules method can be used within a template to determine the number of modules enabled in a given module position. This is commonly used to include HTML around modules in a certain position only if at least one module is enabled for that position. This prevents empty regions from being defined in the template output and is a technique sometimes referred to as “collapsing columns”.

For example, the following code includes modules in the 'user1' position only if at least one module is enabled for that position.

<?php if ($this->countModules( 'user1' )) : ?>
  <div class="user1">
    <jdoc:include type="modules" name="user1" style="rounded" />
  </div>
<?php endif; ?>