# Adding thumbnails to blog posts in a WordPress theme

> Turn on featured images (post thumbnails) in your WordPress theme and display them on your blog posts.

Source: https://helpcenter.ruachost.com/wordpress/guides/adding-thumbnails-to-blog-posts-in-wordpress-theme/

WordPress supports **Post Thumbnails** (also known as **Featured Images**) to visually represent posts, pages, or custom post types. On **ruachost.com**, you can enable and display thumbnails in your theme with a few simple steps.

## Why Use Thumbnails?

- Improves the look of your blog by adding visuals.
- Helps readers quickly identify posts.
- Essential for magazine‑style layouts and grid designs.
- Increases engagement and click‑through rates.

## Enabling Thumbnails in Your Theme

1. **Log in to WordPress** with an administrator account.
2. In the dashboard, go to **Appearance → Theme Editor**.
3. Select your active theme and open the **functions.php** file.
4. Add the following code snippet:

   ```
   // Enable featured images (post thumbnails)
   add_theme_support('post-thumbnails');
   ```
5. Click **Update File** to save changes.

✅ Your theme now supports featured images.

## Displaying Thumbnails in Blog Posts

1. Open the template file where you want thumbnails to appear (e.g., `index.php`, `single.php`, or `content.php`).
2. Insert the following code inside the post loop:

   ```
   <?php if (has_post_thumbnail()) {
       the_post_thumbnail('thumbnail'); // Options: 'thumbnail', 'medium', 'large', 'full'
   } ?>
   ```
3. Save changes.
4. Go to **Posts → Add New** or edit an existing post.
5. In the editor sidebar, set a **Featured Image**.

✅ The thumbnail will now display with your blog posts.

## ⚙️ Customizing Thumbnail Sizes

You can define custom sizes in **functions.php**:

```
// Add custom thumbnail size
add_image_size('custom-thumb', 300, 200, true); // width, height, crop
```

Then call it in your template:

```
the_post_thumbnail('custom-thumb');
```

## Important Notes

- Always back up your theme files before editing.
- Use a **child theme** to preserve changes during updates.
- Thumbnails may need **regeneration** if you change sizes (use the “Regenerate Thumbnails” plugin).
- Featured images are theme‑dependent, some themes already include support.