Bits of .NET

query_posts() breaks main query and causes issues. WP_Query is the proper way to create custom loops.

Wrong Way (Don’t Use):

query_posts('cat=5&posts_per_page=10');
// Breaks pagination, conflicts with main query

Right Way:

$args = array(
    'post_type' => 'post',
    'posts_per_page' => 10,
    'category__in' => array(5)
);

$custom_query = new WP_Query($args);

if ($custom_query->have_posts()) {
    while ($custom_query->have_posts()) {
        $custom_query->the_post();
        the_title();
        the_excerpt();
    }
}
wp_reset_postdata(); // Important!

Clean, doesn’t interfere with main query!