WordPress themes makes it possible to give your users control of many aspects of their site's designs.
One of the most common design features in themes are featured images. Many bloggers love to use large, high-quality images for their posts.
In this tutorial, we will show you how to add featured image support in a custom WordPress theme.
Step #1. Add featured image setting in the dashboard
Edit your theme's functions.php file and add the code below:
function mytheme_post_thumbnails() {
add_theme_support( 'post-thumbnails' );
}
add_action( 'after_setup_theme', 'mytheme_post_thumbnails' );
When you create or edit a post, the new setting will be displayed:

Step #2. Display the featured image in single posts
Look for the theme file that renders individual posts on your site. Often this file is called single.php.
Inside the while() loop add this code:
<?php
if( has_post_thumbnail() ):
echo get_the_post_thumbnail();
endif;
?>
The code above checks whether an image exists for the post/page and then prints it with get_the_post_thumbnail() function.
After your new code is integrated into the loop, it would look similar to this:
<?php
while ( have_posts() ) : the_post();
if( has_post_thumbnail() ):
echo get_the_post_thumbnail();
endif;
endwhile;
?>
Step #3. Check the end result
- Create or edit a post.
- Add a featured image.
- Preview the changes:

Summary
Hopefully this helps you. A stylish Featured Image really helps improve any WordPress post.
Any questions, please feel free to ask in the comments ...