Copyright subsists for a variety of lengths in different jurisdictions. The length of the term can depend on several factors, including the type of work (e.g. musical composition, novel), whether the work has been published, and whether the work was created by an individual or a corporation. In most of the world, the default length of copyright is the life of the author plus either 50 or 70 years. In the United States, the term for most existing works is a fixed number of years after the date of creation or publication. Under most countries' laws (for example, the United States and the United Kingdom), copyrights expire at the end of the calendar year in question.

The length and requirements for copyright duration are subject to change by legislation, and since the early 20th century there have been a number of adjustments made in various countries, which can make determining the duration of a given copyright somewhat difficult. For example, the United States used to require copyrights to be renewed after 28 years to stay in force, and formerly required a copyright notice upon first publication to gain coverage. In Italy and France, there were post-wartime extensions that could increase the term by approximately 6 years in Italy and up to about 14 in France. Many countries have extended the length of their copyright terms (sometimes retroactively). International treaties establish minimum terms for copyrights, but individual countries may enforce longer terms than those.

In the United States, all books and other works published before 1923 have expired copyrights and are in the public domain. In addition, works published before 1964 that did not have their copyrights renewed 28 years after first publication year also are in the public domain, except that books originally published outside the US by non-Americans are exempt from this requirement, if they are still under copyright in their home country (see How Can I Tell Whether a Copyright Was Renewed for more details).

But if the intended exploitation of the work includes publication (or distribution of derivative work, such as a film based on a book protected by copyright) outside the U.S., the terms of copyright around the world must be considered. If the author has been dead more than 70 years, the work is in the public domain in most, but not all, countries. Some works are covered by copyright in Spain for 80 years after the author's death.

In 1998 the length of a copyright in the United States was increased by 20 years under the The Copyright Term Extension Act. This legislation was strongly promoted by corporations which had valuable copyrights which otherwise would have expired, and has been the subject of substantial criticism on this point.

As a curiosity, the famous work "Peter Pan, or The Boy Who Wouldn't Grow Up" has a complex – and disputed – story of copyright expiry.

Duration
Transfer and licensing, and assignment
Copyright term
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