How to add the rel=”nofollow” attribute to your tags.
You’ll need to edit your category-template.php file. This is usually found here:
\wp-includes\category-template.php
Edit line 416 of the file so it reads:
$rel = ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) ? ' rel="nofollow"' : '';
Edit line 528 of the file so it reads:
$term_links[] = '<a href="' . $link . '" rel="nofollow">' . $term->name . '</a>';
Now all your tags have the rel=”nofollow” attribute.
Why would you need to do this? Without nofollow, Google will pagerank your tag pages, regardless of what’s in your robots.txt or sitemap.xml file, and thus they’ll appear in Google search results (usually with a higher page rank than your actual blog posts).