A post whose source doesn't directly link to the image or page where the image is from. This includes redirect links and links to an artist's gallery or profile page.
Examples include:
Artist profile pages
https://otherguy.deviantart.com
https://www.pixiv.net/users/1234
https://twitter.com/noguy
https://gumroad.com/noguy
https://www.patreon.com/noguy
Gallery pages
https://otherguy.deviantart.com/gallery
https://www.pixiv.net/en/users/1234/artworks
https://twitter.com/noguy/media
Redirect links
https://www.google.com/imgres?imgurl=longurl
This tag is automatically added to posts for sites that Danbooru recognizes, and cannot be removed from those posts. It can be freely added or removed to posts for sites Danbooru doesn't recognize.
See also
bad link, where the source is correct but leads to a direct image instead of the post
bad id, where the source was correct in the past but has since been deleted (404)
source mismatch, where the source was correct in the past but now points to a different image/collection
