Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative expression, including books, video, movies, music and computer programs. Historically, copyright law has been enacted to balance the desire of cultures to use and reuse creative works (thus creating "derivative work") against the desire of the creators of art, literature, music and the like to monetize their work by controlling who can make and sell copies of the work.

To strike this balance, the exclusivity of control is almost always restricted to a set period of years, after which a copyright-protected work reverts to the public domain and may be freely used. Under current law in the U.S., works created after Jan. 1, 1978, are afforded copyright protection for the life of the author plus an additional 70 years. For anonymous, pseudonymous and corporate-owned works, a copyright lasts 95 years from the year of its first publication or a term of 120 years from the year of its creation, whichever expires first.

The copyright holder is often a company or corporation. If a work is created as a component of employment ("work for hire"), then the copyright for the work defaults to the employer.

Copyright ownership is bounded by the territory of the jurisdiction in which it has been granted (a copyright granted by the United States is valid only within that country, for example), as well by certain specific exceptions. Much of international copyright law was brought into relative conformity with the Berne Convention for the Protection of Literary and Artistic Works (usually referred to as the Berne Convention), in 1886 (with numerous subsequent revisions over the decades). The World Intellectual Property Organization Copyright Treaty (also known as the WIPO Copyright Treaty or WCT) was adopted in 1996 to cover information technology and the internet, elements not directly addressed in the Berne Convention.

The copyright symbol, a 'c' wrapped in a circle.The copyright symbol, used
to assert copyright ownership.

An important shift in copyright legislation that appeared in the Berne Convention was the move to make copyright protection automatic. In most countries today, creators do not need to register or apply for copyright protection of a work. Rather, the author of a work is immediately entitled to all copyrights of the work until those rights are explicitly disclaimed or the copyright expires.

Before 1989, United States law required the use of a copyright notice to assert that copyright was being claimed. The copyright symbol or the word "copyright" had to be placed somewhere within the protected work, along with the year the work was created or published.

Copyright duration and public domain

The notion of protecting publishers from unauthorized third-party sales of copies of their books dates back to the 1709 Statute of Anne in Britain, a law that gave publishers exclusive publishing rights for a fixed period, after which their work could be produced and sold by others. In the United States, the first legislation along these lines appears in the U.S. Constitution, in Article I, Section 8, Clause 8, where the so-called Copyright Clause gives Congress the authority to enact laws "securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries."

Both these laws, along with current copyright legislation worldwide, call for protected works to enter the "public domain" after the copyright law's stipulated term has passed. Works in the public domain may be used, copied and distributed with no restrictions under copyright law.

Copyright exceptions and fair use

Not every expression of an idea may be copyright protected. Copyright doesn't protect:

  • Product names
  • Titles of works (such as book titles)
  • Names of businesses and organizations
  • Pseudonyms, including computer hacker "nyms."
  • Slogans, catchphrases, mottos and short advertising phrases
  • Lists of ingredients, such as on product labels or as used in recipes

Some things on this list, such as product names, may be afforded protection under trademark law.

Even when a work is protected under copyright law, the copyright law allows certain exceptions where works may be used even when the copyright holder has otherwise restricted use. Some of these exceptions are a matter of practicality, such as allowing libraries to make Braille copies of books they own. In some cases, such as public venues that play music through jukeboxes, the copyright owner is compelled by the law to grant the jukebox owner a license at a predetermined fee.

One important set of exceptions is the allowance for making backup copies of digital works that are copyright protected.

The most important exception is "fair use," known in some other international jurisdictions as "fair dealing." Conceptually, fair use is a refinement of the basic balance copyright strikes between author and civil interests. It is in the public's interest to have access to critical reviews of works, and in considering these works, the critic may include short excerpts of a work in order illustrate a point being made. Copyright laws also generally protect works of parody from copyright infringement claims, as is the use of works for educational uses.

It is important to note, though, that what counts as fair use is generally not well delineated in copyright laws around the world. In the U.S., the law lists four basic guidelines courts may use in lawsuits where infringement is alleged:

  1. the purpose and character of the use, including whether it is commercial or noncommercial;
  2. the nature of the work (e.g., factual works are entitled to less protection than purely creative works);
  3. the amount and substantiality of the portion of the work used; and
  4. the effect of the use upon the potential market for the work.

In the world of popular music, the boundaries of fair use have been tested as a result of the use of "samples" or short snippets of copyright-protected songs in new works. Clear precedents have not been established because court decisions have taken unpredictable turns. A 2005 decision in the 6th District Court in the U.S. held that copying even as few as three consecutive notes could constitute infringement. Other cases have revolved around whether permissions must be obtained for portions of a work that are sampled or for the underlying song, or both. Generally, commercial musicians generally buy "clearances" to sample works, meaning that whether that sampling could be allowed under fair use provisions is simply not tested.

Digital rights management as copyright control

Digital expressions, such as ebooks and music, are of course protected under copyright just as their traditional book and compact disc counterparts are. Controlling infringement and unauthorized reproduction of digital works is considerably more difficult than hard copy products that require printing and physical distribution. Copyright protects these works and can be used as the basis for lawsuits after the fact, but corporations have embraced the idea of using digital technologies to protect digital works.

There are two basic approaches used in typical DRM products:

  1. Individual copies of the digital product are encrypted and contain the code necessary to protect their use. The protections used to prevent unauthorized duplication of commercially distributed DVDs are examples of this and rely on safeguards built into DVD players to prevent the use of pirated copies.
  2. A centralized rights management server checks authorizations at time of use and locks or unlocks digital copies accordingly. This allows finer-grained control and better overall use accounting but requires internet connection before each use.

There are, in some DRM systems, additional controls enforced. Books read in the Amazon Kindle ecosystem, for instance, can be "highlighted" within the context of the present copy, but copying text displayed in a Kindle reader to the clipboard of the operating system isn't allowed.

This DRM-imposed restriction on cutting and pasting is, critics have noted, a restriction that goes beyond the rights provided under copyright law, where that cutting and pasting might well fall into the realm of fair use. Not being able to make backup copies of DVDs is another case where use of a work is allowed under copyright but may be prohibited by the DRM system a corporation has opted to use.

Further, the Digital Millennium Copyright Act of 1998 (DMCA) includes a stipulation that makes it a criminal offense to reverse engineer DRM systems, even if the aim is to take actions that are allowed under that same copyright law. Manufacturers of goods such as farm tractors and cars that one wouldn't normally associate with copyright protections have asserted that the DMCA reverse engineering provision applies to software used in embedded systems within their products. Thus, third-party attempts to understand those systems are criminal offenses, not because of copyright infringement but simply because research on the workings of DRM systems is illegal.

A number of prosecutions (and threatened legal actions) have been mounted since the DMCA was enacted. A partial list of these is maintained by the Electronic Frontier Foundation.

In October 2016, the Library of Congress temporarily authorized security researchers who were "acting in good faith" to conduct some kinds of research on consumer devices so long as the research did not violate other laws such as the Computer Fraud and Abuse Act (CFAA). 

There is a four-part test for whether any given research falls under the exemption:

1)     The computer program must be lawfully acquired.

2)     The actions taken must be "solely for the purpose of good-faith security research."

3)     The research must take place after Oct. 28, 2016.

4)     While not technically a requirement, the authorization implies that responsible disclosure is an important element in establishing that the work was done in good faith.

Good faith is circularly defined as being "solely for the purposes of good-faith testing," but is also explained to mean the work can't be done "in a manner that facilitates copyright infringement."

Only research conducted with primarily consumer-oriented products fall under this authorization.

Copyleft and creative commons

An interesting exception of sorts to copyright is a concept originally championed by Richard Stallman and the Free Software Foundation, which created copyleft as a means of effectively stripping most copyright restrictions from a work to allow free use (including copying) of the material, while retaining control over how the material is shared.

Under the copyleft, derivative works created using that original work must also be given copyleft protection. More broadly, this approach is known as "free" licensing, and is considered a form of open source license.

Material published under open source licenses may be freely copied, modified, shared and distributed, as long as the original license is applied to the distributed material. When used for publishing software, the copyleft license also requires that source code be included (or made available) when modified software is published.

In 2001, Creative Commons, a nonprofit organization, was created to facilitate several kinds of legal sharing so that works could be freely reused, but in contexts that are controlled by the copyright holder. Works covered under Creative Commons licenses are aggregated at

This was last updated in May 2017

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