Settings - Thumbnail compression
Each image has a number of thumbnails automatically generated by WordPress upon uploading it. By default, WordPress generates up to 7 thumbnails, but this number can increase depending on the theme and plugins you use on your website.
You can identify a thumbnail because it has a number attached to it. Example:
- Original: https://blog.shortpixel.com/wp-content/uploads/2021/12/1-1.png
- Thumbnail: https://blog.shortpixel.com/wp-content/uploads/2021/12/1-1-2048x915.png
These thumbnails are not useless. In fact, most web pages display them instead of the original pictures; when your site gives you the option to choose an image size to display, you are choosing the thumbnail. It is highly recommended that you optimize the thumbnails by enabling this setting, as they are usually the images most viewed by end users and can generate most traffic.
Please note that thumbnails count up to your total quota. For more information, see how ShortPixel Image Optimizer counts your credits.