How to Display Related Posts in WordPress Without a Plugin

1. Display Related Post by Tags
2. Display Related Post by Categories

You need to open your single.php files in WordPress editor and paste these lines of code where you want to display related posts on your website.

In Latest Version of Wordpress, you need to open your content-single.php files in WordPress editor and paste these lines of code where you want to display related posts on your website.

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),
'showposts'=>4, // Number of related posts that will be shown.
'caller_get_posts'=>1
);
$my_query = new wp_query($args);
if( $my_query->have_posts() ) {
echo '
Related Posts
';
while ($my_query->have_posts()) {
$my_query->the_post();
?>




';
}
}
wp_reset_query();
?>

ID);
if ($categories) {
$category_ids = array();
foreach($categories as $individual_category) 
$category_ids[] = $individual_category->term_id;
$args=array(
'category__in' => $category_ids,
'post__not_in' => array($post->ID),
'posts_per_page'=> 5, // Number of related posts that will be displayed.
'caller_get_posts'=>1,
'orderby'=>'rand' // Randomize the posts 
);
$my_query = new wp_query($args);
if( $my_query->have_posts() ) {
echo '
Related Posts
';
while ($my_query->have_posts()) {
$my_query->the_post();
?>
















'; 
} }  
wp_reset_query(); 
?>