What is Copyright?
Copyright is a legal protection granted by U.S. law, intended to prevent infringement on the rights of authors and creators of original works. The laws dictate specifically which works are eligible for protection, who can claim copyrights as creators, the individual rights protected by the law, as well as the amount of time such protections will last. The law imposes steep penalties against those who violate the copyrights of others.
According to law, any original work of authorship, that is - works independently created with some degree of originality or creativity - are automatically protected under U.S. Copyright law. This includes, but is not limited to:
Chances are that you yourself may own the copyrights to previous works you have done - a term paper, a journal article, a drawing of your cat, or even a family video you took on your last vacation. If it is something that you made yourself, that is original and creative, it is likely protected.
Copyright law in the United States generally protects the copyright holder's sole rights to:
Under U.S. Copyright law, the copyright holder has the exclusive right to perform these actions with regard to the work the holds the rights to. However, there are some exceptions - particularly for educational purposes. See - The Fair Use Exception.
Copyright law only protects things that are both fixed in form and original works. Therefore, it does not protect thing such as:
Copyright law also does not apply to most works created by employees of the United States Government as part of their employment. These works are automatically put into the public domain.
The general rule is that, for works created and published in the United States after 1978, copyright is protected for the entire life of the author(s), plus an additional 70 years. If the author is anonymous, a pseudonym, or the work is a work-for-hire, it is protected for 95 years from publication - or - 120 years from creation, whichever is shortest.
For all other works, copyright varies based on the circumstances in which it was created. See the "Copyright Term and the Public Domain in the United States" chart created by Cornell University to explore the copyright duration of other works.
After the copyright of a work has expired (and if the work is not further covered by any other protections - such as trademarks), the work then passes into the public domain and may be used in any legal way without permission. Once in the public domain, no one individual has any rights to the work.
Works produced by U.S. government employees automatically fall into the public domain if produced as part of their employment.
A growing number of copyright holders have decided to reject their copyrights and to deliberately place their work into the public domain, usually done via a written notice accompanying the work.
NOTE: If a work does not fall into one of these categories, or if you are unsure, you must assume it is protected by copyright and treat it accordingly.