WordPress post thumbnails or featured images can add more beauty and interactivity to a WordPress theme. If you have WordPress thumbnails enabled in your theme, you may add a relevant image for it to appear with the post in the indices like homepage, categories and other archive pages.
We don’t have the post thumbnails enabled by default with WordPress themes, and developer has to do a bit more work to enable them. It’s not like you have to code a whole function for it, you just have to add theme support for thumbnails. It sounds very simple, isn’t it?
To activate WordPress post thumbnails for your theme, all you need to do is add the below code in the
functions.php file of your theme:
add_theme_support( 'post-thumbnails' );
And save the changes. Now, compose a new post and you will see a new meta box called Featured Image at the bottom-right side of the post editor. You may add a featured image by clicking Set featured images link there and then choose or upload the image.
After enabling the thumbnails, you can also add a featured thumbnail to your existing post.