Copyright protection in the U.S. exists automatically from the moment an original work of authorship is fixed in a tangible medium. Registration of copyright with the U.S. Copyright Office is voluntary. There are cases in which registration is recommended, but it is never required.
The U.S. Copyright Law governs the making of photocopies, scans or other reproductions of copyright material. Certain copying may be an infringement of copyright law. For works published in 1978 and later, copyright lasts for the life of the author plus 70 years. The copyright term for corporations (works for hire) is 120 years from creation or 95 years from publication, whichever is later.
A copyright owner may grant rights to the public to use a protected work. That grant could be a simple statement on the work explaining the allowed uses, or it may be a selection of a Creative Commons license. Similarly, the movement to make works "open access" or "open source" is a choice by the owner of rights to make works available to the public.
Some works lack copyright protection, and they are freely available for use without the limits and conditions of copyright law. Copyright eventually expires too. When a work lacks copyright protection or where copyright has expired, it is said that the work enters the public domain. The Stanford University Libraries provides a detailed guide on identifying public domain materials. According to this guide, there are four common ways that works arrive in the public domain:
For example, works produced by the U.S. federal government are not copyrightable. Copyright also does not protect facts, ideas, discoveries, and methods.
In general, the U.S. Copyright Law applies to domestic and foreign works. Under major multinational treaties, many countries have agreed to give copyright protection to works from most other countries of the world. Because the U.S. has joined such treaties, you should apply same principles of copyright to most works, regardless of their country of origin.
It is an infringement of copyright to copy all or a substantial part of a copyright protected work or to communicate all or a substantial part of a copyright protected work to the public by telecommunication without the consent of the holder of the copyright, unless copying or communicating the work falls within an exemption from copyright infringement. One of the main exemptions is the Fair Use provisions or specific educational exceptions, as discussed on the other pages of this guide.