What is copyright?
Copyright is a form of intellectual property protection provided by the laws of the United States (title 17, U.S. Code) to the creators of "original works of authorship," including literary, dramatic, musical, artistic, and certain other intellectual works. Copyright grants creator/authors the ability to control the use of the work created and gives to authors certain exclusive rights:
Make copies (ex. a download, PDF email attachment, photocopy or scan, etc.)
Distribute copies (ex. sharing on the internet, sending in an email)
Prepare derivatives based on the original work (ex. a translation, a sequel, a spin-off)
Perform the work publicly (ex. act out, read aloud, play for an audience)
Display the work publicly (ex. posting on a website)
Copyright protection exists when a work is fixed in a tangible form of expression (Including a DVD, CD, or even a napkin with writing on it).
What is protected?
Under the copyright act, section 102, original works of authorship fixed in any tangible medium of expression now known or later developed are protected. These works include the following categories:
Copyright does not protect ideas, procedures, processes, methods, concepts, useful objects, or facts. Copyright protection is also not available for any work created by the U.S. Federal Government. However, publications made by third parties under government contracts and by state governments (for example) are considered differently by the law and may be protected by copyright.
How long is a work protected by copyright?
Works are protected for the life of the author plus 70 years per the 1998 Copyright Term Extension Act which applied to works created from 1978 onwards. The protected status of works published before 1978 and after 1923 varies in accordance with how they were published, registered, and renewed.
Unpublished materials, like diaries and correspondence, prior to 1978 are protected for the life of the author plus 70 years. When a work is no longer protected by copyright due to copyright expiring, it falls into the public domain. See What is the Public Domain for more.
Copyright law and duration vary per country. However, several countries have worked together to create international agreements that align policies across borders. Foreign works are, for the most part, protected for the same term as works published within the user's country for all signatories of the Berne and TRIPS agreements. The U.S. is both an adopter of the Berne convention and a signatory of the TRIPS agreement.