Orphan works are creative works that are still under copyright protection, but for which it is either impossible or prohibitively difficult to identify the copyright holder.
This is most often a problem with photographs on the Internet, but arises with other types of works as well. Since the works are under copyright, permission is need to use them, but since the rights-holder cannot be found, no permission can be obtained. This puts these works into a sort of limbo. People want to make use of them, but usually won’t for fear of liability, and the works cannot pass into the public domain until the term of their copyright expires.
The settlement with the Author’s Guild in the Google Book Search lawsuit contains controversial provisions for orphan works, although it does not refer to them by that term. These terms are the subject of much debate and opposition worldwide.
Orphan works legislation has also been proposed at several different times in the U.S. Congress.