How to add Related Post in Wordpress Without a pluin

You can done this by tow ways , one by tags and another by category. So how to do this?

related post in wordpress by Category

1. Add this code in functions.php

    add_theme_support( 'post-thumbnails' );  
    set_post_thumbnail_size( 150, 150, true );

2. Then add this codode in single.php

    

Related posts
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'=> 4, // Number of related posts that will be shown.
    'caller_get_posts'=>1
    );
	
	$my_query = new wp_query( $args );

	while( $my_query->have_posts() ) {
	$my_query->the_post();
	?>
	
	

		

		
		
	
	
	

3.Add Some css to your style.css

.relatedposts {width: 640px; margin: 0 0 20px 0; float: left; font-size: 12px;}
.relatedposts h3 {font-size: 20px; margin: 0 0 5px 0; }
.relatedthumb {margin: 0 1px 0 1px; float: left; }
.relatedthumb img {margin: 0 0 3px 0; padding: 0;}
.relatedthumb a {color :#333; text-decoration: none; display:block; padding: 4px; width: 150px;}
.relatedthumb a:hover {background-color: #ddd; color: #000;}

                  
				  

related post in wordpress by tag

add this code in functions.php

    add_theme_support( 'post-thumbnails' );  
    set_post_thumbnail_size( 150, 150, true );

                  
				  

Then add this codode in single.php

Related posts
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'=>4, // Number of related posts to display.
	'caller_get_posts'=>1
	);
	
	$my_query = new wp_query( $args );

	while( $my_query->have_posts() ) {
	$my_query->the_post();
	?>
	
	

		

		
		
	
	
	






 3 Some css style 





                  
				
.relatedposts {width: 640px; margin: 0 0 20px 0; float: left; font-size: 12px;}
.relatedposts h3 {font-size: 20px; margin: 0 0 5px 0; }
.relatedthumb {margin: 0 1px 0 1px; float: left; }
.relatedthumb img {margin: 0 0 3px 0; padding: 0;}
.relatedthumb a {color :#333; text-decoration: none; display:block; padding: 4px; width: 150px;}
.relatedthumb a:hover {background-color: #ddd; color: #000;}