Learning if a work is covered by copyright is likely to interest you as both a producer of original content and a user of content written or created by others. According to the United States Copyright Office, a “work is under copyright protection the moment it is created and fixed in a tangible form that it is perceptible either directly or with the aid of a machine or device.”
Ideas and facts are not protected by copyright, but once they are expressed in a tangible form such as a book, an article, a photograph, a painting, a work of music, a dance, an architectural work, a film or a computer program they are protected. Furthermore, a work does not have to be published to be protected by copyright.
A work does not have to be registered with the US Copyright Office in order for it to be protected. Registration is voluntary, but a lawsuit for infringement can only be brought if a work is registered. Authors will find copyright registration forms here and a list of fees here.
There was a time when copyright notice was required on a publication in order for it to have copyright protection. This is no longer true. However, if you are interested in determining the copyright status of a document not marked with a copyright notice, Circular 3 from the US Copyright Office should help you decide if a work is covered or not.
Works will fall out of copyright and into the public domain depending on their date of publication. Works that were created before 1923 are not covered by copyright . Works published between 1923 and 1978 without a notice and registration are also no longer covered by copyright.
For more information on public domain, see the Stanford University site Welcome to the Public Domain.