single.php

<?php get_header(); ?>

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
	<div class="u-container u-section">
		<h1><?php the_title(); ?></h1>
		<?php the_content(); ?>
		<p>Posted on <?php echo get_the_time('jS F Y'); ?></p>
	</div>
	<div class="u-container u-section">
		<h2>Related articles</h2>
		<ul class="u-list-unstyled">
	    <?php
            $$orig_post = $post;
	        global $post;
	        $tags = wp_get_post_tags($post->ID);

	        if ($tags) {
	            $tag_ids = array();
	        foreach($tags as $individual_tag) $tag_ids[] = $individual_tag->term_id;
	            $args=array(
	                'tag__in' => $tag_ids,
	                'post__not_in' => array($post->ID),
	                'posts_per_page'=>5, // Number of related posts to display.
	                'caller_get_posts'=>1,
					'orderby' => 'rand'
	            );

	        $my_query = new wp_query( $args );

	        while( $my_query->have_posts() ) {
	            $my_query->the_post();
	        ?>
	        	<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
	        <?php }
	        }
	        $post = $orig_post;
	        wp_reset_query();
	    ?>
		</ul>
	</div>
<?php endwhile; else : ?>
	<div class="u-container">
		<h1>Not Found</h1>
		<p>Sorry, but you are looking for something that isn't here.</p>
	</div>
<?php endif; ?>

<?php get_footer(); ?>