<?php
/* Useful code snippet if you want to display the category title on top
 * of a featured image on a list of post.
 * If a post is in more than one category, this snippet
 * selects the first one. If no cateogry is set, the default category appears.
 */

		$post_categories = wp_get_post_categories( $post->ID );
		// get first category id
		$first_cat = get_category($post_categories[0]);
		// get category term info.
		$term_link = get_term_link( $first_cat->slug, $first_cat->taxonomy );

		echo "<a href='".$term_link."'>".$first_cat->name."</a>";
?>