All copyrights must be an original work of authorship, fixed in any tangible medium of expression from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device.
The key feature is fixed in any tangible medium. Music is not copyrightable until it is recorded, either as notes on paper or sound on a CD. Ideas are not protected, unless written. Fictional characters must be fully described in a book or story.
There are eight statutory groups of copyrights (Title 17 of the U.S. Code Section 102).
Some objects and items do not receive copyright protection at all. Particular forms of expression are so common that granting a 70 year protection period would interfere with most daily activities. The following are examples of items that do not receive copyright protection.
Duration of a Copyright
Copyrights last for a much longer time than patents. The maximum term for a patent is 20 years. Copyrights typically last 70 years after the author's death.
If there were co-creators, the expiration is 70 years after the last survivor's death.
Works that were made for hire, anonymous, or pseudonymous expire 95 years after publication or 120 years from creation (whichever ends first).
If the work was created, but not published or registered, before 1978 it will expire not earlier than 70 years after the creator's death. If the work was not published before 12/31/2002, it is already expired. If the work was published before 12/31/2002, it will expire not earlier than 12/31/2047.
Works that were published between 1964 and 1977, expire 95 years from publication.
If published between 1923 and 1963 and renewed, it expires 95 years from the date of first publication. If not renewed, the copyright is expired.
Anything that was published before 1923 is in the public domain.
Not Absolute Protection
Copyright law, unlike patents and trademarks, does not grant an absolute exclusive right. Under certain scenarios, individuals are allowed to use your work under "fair use".
Infringement does not exist if material is used for criticism, comment, news reporting, teaching, scholarship, or research. Courts consider the following factors to determine whether fair use or infringement has occurred.
(1) Purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes
(2) Nature of the copyrighted work
(3) Amount and substantiality of the portion used in relation to the copyrighted work as a whole
(4) Effect of the use upon the potential market for or value of the copyrighted work
If you modify a copyrighted work, that revision is not protected unless it is registered as new material with a separate application. Every time a copyrighted work is revised, a new application is required.
A derivative work is based on an existing copyright and can be registered if different enough from the original or contains a substantial amount of new material to be considered new. Rights only cover what is new. Here are some examples.
Federal Statutes: U.S. Code Title 17
Federal Code of Regulations: CFR Title 37