I was told this : "Basically here Attach/Detach refers to the registration of the media file to the particular post while uploading to the Media Library and not whether it is used in the post or not."
However, I inserted an unattached image into a post and it becomes attached even if I didn't upload it to that post or page. So, it seems that its not just for media uploaded to...
I have many images which show their status as unattached in the media library, but they are either featured images in posts or pages or images in the postal page.
(More digging: In the database, wp_postmeta, it looks like the _thumbnail_id keeps track of the thumbnail for the post. post_parent is where the ‘uploaded to’ field is kept. Even though in wp_posts, post_parent field for the image is 0. my posts are finding their images fine. Looks like the other images associated with a post are in the post_content field.)
Should I manually attach them or does this matter to WordPress, integrity or functioning ? Basically, is this field just informational?
( Note: I'm new to this forum and cannot comment, since you need 50 reputation points...)