Gallery with shortcode not showing

While gallery shortcode does have id arguments, it won’t do what you think. If that argument is present WP will try to look for child attachments of that post, using get_children(). It won’t take content of the post and shortcodes in it into account. If the gallery is only content of that page you could … Read more

For what does WP generate Thumbnails?

Unless you have embedded images at the medium size into posts or pages, then WP will not use these images sizes as far as I am aware in any place in the admin. I think it should be safe to delete the medium size images completely. Also, I am happy you are using FooGallery – … Read more

Specify which image sizes are created on a per image basis

WordPress isn’t natively friendly to such granular size management. Also it could take a considerable toll on humans to manage it, if manual. The common approach is to switch image sizes generation from the moment of upload to the moment of size being requested. So the sizes which are never actually used are never generated … Read more

Change Featured Image Size of the Post

In you WordPress Admin, Go to Settings > Media, here you can set the default size of ‘thumbnail’,’medium’ and ‘large’. If you read through the codex page of the_post_thumbnail() you would have found that it has parameters that can be used to fetch a precised size of the image. the_post_thumbnail(); // without parameter -> ‘post-thumbnail’ … Read more