A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work".^[1] A CC license is used when an author wants to give other people the right to share, use, and build upon a work that they (the author) have created. CC provides an author flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work.^{[2][3][4][5][6]}

There are several types of Creative Commons licenses. The licenses differ by several combinations that condition the terms of distribution. They were initially released on December 16, 2002 by Creative Commons, a U.S. non-profit corporation founded in 2001. There have also been five versions of the suite of licenses, numbered 1.0 through 4.0.^[7] As of December 2018, the 4.0 license suite is the most current.

In October 2014, the Open Knowledge Foundation approved the Creative Commons CC BY, CC BY-SA and CC0 licenses as conformant with the "Open Definition" for content and data.^[8][9][10]

Work licensed under a Creative Commons license is governed by applicable copyright law.^[11] This allows Creative Commons licenses to be applied to all work falling under copyright, including: books, plays, movies, music, articles, photographs, blogs, and websites.

While Software is also governed by copyright law and CC licenses are applicable, the Creative Commons recommends Free and open-source software software licenses instead of Creative Commons licenses.^[12] Outside the FOSS licensing use case for software there are several usage examples to utilize CC licenses to specify a "Freeware" license model; examples are The White Chamber, Mari0 or Assault Cube.^[13] Also the Free Software Foundation recommends the CC0^[14] as the preferred method of releasing software into the public domain.^[15]

There are over 35,000 works that are available in hardcopy and have a registered ISBN number. Creative Commons splits these works into two categories, one of which encompasses self-published books.^[16]

However, application of a Creative Commons license may not modify the rights allowed by fair use or fair dealing or exert restrictions which violate copyright exceptions.^[17] Furthermore, Creative Commons licenses are non-exclusive and non-revocable.^[18] Any work or copies of the work obtained under a Creative Commons license may continue to be used under that license.^[19]

In the case of works protected by multiple Creative Commons licenses, the user may choose either.^[20]

The CC licenses all grant the "baseline rights", such as the right to distribute the copyrighted work worldwide, for non-commercial purposes and without modification.^[21] The details of each of these licenses depend on the version, and comprises a selection out of four conditions:

The last two clauses are not free content licenses, according to definitions such as DFSG or the Free Software Foundation's standards, and cannot be used in contexts that require these freedoms, such as Wikipedia. For software, Creative Commons includes three free licenses created by other institutions: the BSD License, the GNU LGPL, and the GNU GPL.^[23]

Mixing and matching these conditions produces sixteen possible combinations, of which eleven are valid Creative Commons licenses and five are not. Of the five invalid combinations, four include both the "nd" and "sa" clauses, which are mutually exclusive; and one includes none of the clauses. Of the eleven valid combinations, the five that lack the "by" clause have been retired because 98% of licensors requested attribution, though they do remain available for reference on the website.^[24][25][26] This leaves six regularly used licenses + the CC0 public domain waiver:

^[26][27]

For example, the Creative Commons Attribution (BY) license allows one to share and remix (create derivative works), even for commercial use, so long as attribution is given.^[28]

The original non-localized Creative Commons licenses were written with the U.S. legal system in mind; therefore, the wording may be incompatible with local legislation in other jurisdictions, rendering the licenses unenforceable there. To address this issue, Creative Commons asked its affiliates to translate the various licenses to reflect local laws in a process called "porting."^[29] As of July 2011, Creative Commons licenses have been ported to over 50 jurisdictions worldwide.^[30]

The latest version 4.0 of the Creative Commons licenses, released on November 25, 2013, are generic licenses that are applicable to most jurisdictions and do not usually require ports.^{[31][32][33][34]} No new ports have been implemented in version 4.0 of the license.^[35] Version 4.0 discourages using ported versions and instead acts as a single global license.^[36]

Since 2004, all current licenses other than the CC0 variant require attribution of the original author, as signified by the BY component (as in the preposition "by").^[25] The attribution must be given to "the best of [one's] ability using the information available".^[37] Generally this implies the following:

The "non-commercial" option included in some Creative Commons licenses is controversial in definition,^[38] as it is sometimes unclear what can be considered a non-commercial setting, and application, since its restrictions differ from the principles of open content promoted by other permissive licenses.^[39] In 2014 Wikimedia Deutschland published a guide to using Creative Commons licenses as wiki pages for translations and as PDF.^[40]

Besides licenses, Creative Commons also offers through CC0 a way to release material worldwide into the public domain.^[27] CC0 is a legal tool for waiving as many rights as legally possible.^[42] Or, when not legally possible, CC0 acts as fallback as public domain equivalent license.^[42] Development of CC0 began in 2007^[43] and was released in 2009.^[44][45] A major target of the license was the scientific data community.^[46]

In 2010, Creative Commons announced its Public Domain Mark,^[47] a tool for labeling works already in the public domain. Together, CC0 and the Public Domain Mark replace the Public Domain Dedication and Certification,^[48] which took a U.S.-centric approach and co-mingled distinct operations.

In 2011, the Free Software Foundation added CC0 to its free software licenses,^[14] and currently recommends CC0 as the preferred method of releasing software into the public domain.^[15]

In February 2012 CC0 was submitted to Open Source Initiative (OSI) for their approval.^[49] However, controversy arose over its clause which excluded from the scope of the license any relevant patents held by the copyright holder. This clause was added with scientific data in mind rather than software, but some members of the OSI believed it could weaken users' defenses against software patents. As a result, Creative Commons withdrew their submission, and the license is not currently approved by the OSI.^[46][50]

In 2013, Unsplash began using the CC0 license to distribute free stock photography.^[51][52] It now distributes several million photos a month^[53] and has inspired a host of similar sites, including CC0 photography companies and CC0 blogging companies.^[54] Lawrence Lessig, the founder of Creative Commons, has contributed to the site.^[55] Unsplash moved from using the CC0 licence to their own similar licence in June 2017, but with a restriction added on using the photos to make a competing service which makes it incompatible with the CC0 licence.^[56]

In October 2014 the Open Knowledge Foundation approved the Creative Commons CC0 as conformant with the "Open Definition" and recommend the license to dedicate content to the public domain.^[9][10]

Rights in an adaptation can be expressed by a CC license that is compatible with the status or licensing of the original work or works on which the adaptation is based.^[57]

The legal implications of large numbers of works having Creative Commons licensing are difficult to predict, and there is speculation that media creators often lack insight to be able to choose the license which best meets their intent in applying it.^[60]

Some works licensed using Creative Commons licenses have been involved in several court cases.^[61] Creative Commons itself was not a party to any of these cases; they only involved licensors or licensees of Creative Commons licenses. When the cases went as far as decisions by judges (that is, they were not dismissed for lack of jurisdiction or were not settled privately out of court), they have all validated the legal robustness of Creative Commons public licenses. Here are some notable cases:

In early 2006, podcaster Adam Curry sued a Dutch tabloid who published photos from Curry's Flickr page without Curry's permission. The photos were licensed under the Creative Commons Non-Commercial license. While the verdict was in favor of Curry, the tabloid avoided having to pay restitution to him as long as they did not repeat the offense. Professor Bernt Hugenholtz, main creator of the Dutch CC license and director of the Institute for Information Law of the University of Amsterdam, commented, "The Dutch Court's decision is especially noteworthy because it confirms that the conditions of a Creative Commons license automatically apply to the content licensed under it, and binds users of such content even without expressly agreeing to, or having knowledge of, the conditions of the license."^{[62][63][64][65]}

In 2007, Virgin Mobile Australia launched an advertising campaign promoting their cellphone text messaging service using the work of amateur photographers who uploaded their work to Flickr using a Creative Commons-BY (Attribution) license. Users licensing their images this way freed their work for use by any other entity, as long as the original creator was attributed credit, without any other compensation required. Virgin upheld this single restriction by printing a URL leading to the photographer's Flickr page on each of their ads. However, one picture, depicting 15-year-old Alison Chang at a fund-raising carwash for her church,^[66] caused some controversy when she sued Virgin Mobile. The photo was taken by Alison's church youth counselor, Justin Ho-Wee Wong, who uploaded the image to Flickr under the Creative Commons license.^[66] In 2008, the case (concerning personality rights rather than copyright as such) was thrown out of a Texas court for lack of jurisdiction.^[67][68]

In the fall of 2006, the collecting society Sociedad General de Autores y Editores (SGAE) in Spain sued Ricardo Andrés Utrera Fernández, owner of a disco bar located in Badajoz who played CC-licensed music. SGAE argued that Fernández should pay royalties for public performance of the music between November 2002 and August 2005. The Lower Court rejected the collecting society's claims because the owner of the bar proved that the music he was using was not managed by the society.^[69]

In February 2006, the Cultural Association Ladinamo (based in Madrid, and represented by Javier de la Cueva) was granted the use of copyleft music in their public activities. The sentence said: "Admitting the existence of music equipment, a joint evaluation of the evidence practiced, this court is convinced that the defendant prevents communication of works whose management is entrusted to the plaintiff [SGAE], using a repertoire of authors who have not assigned the exploitation of their rights to the SGAE, having at its disposal a database for that purpose and so it is manifested both by the legal representative of the Association and by Manuela Villa Acosta, in charge of the cultural programming of the association, which is compatible with the alternative character of the Association and its integration in the movement called 'copy left'".^[70]

On June 30, 2010 GateHouse Media filed a lawsuit against That's Great News. GateHouse Media owns a number of local newspapers, including Rockford Register Star, which is based in Rockford, Illinois. That's Great News makes plaques out of newspaper articles and sells them to the people featured in the articles.^[71] GateHouse sued That's Great News for copyright infringement and breach of contract. GateHouse claimed that TGN violated the non-commercial and no-derivative works restrictions on GateHouse Creative Commons licensed work when TGN published the material on its website. The case was settled on August 17, 2010, though the settlement was not made public.^[71][72]

The plaintiff was photographer Art Drauglis, who uploaded several pictures to the photo-sharing website Flickr using Creative Commons Attribution-ShareAlike 2.0 Generic License (CC BY-SA), including one entitled "Swain's Lock, Montgomery Co., MD.". The defendant was Kappa Map Group, a map-making company, which downloaded the image and used it in a compilation entitled "Montgomery Co. Maryland Street Atlas". Though there was nothing on the cover that indicated the origin of the picture, the text "Photo: Swain's Lock, Montgomery Co., MD Photographer: Carly Lesser & Art Drauglis, Creative Commoms [sic], CC-BY-SA-2.0" appeared at the bottom of the back cover.

The validity of the CC BY-SA 2.0 as a license was not in dispute. The CC BY-SA 2.0 requires that the licensee to use nothing less restrictive than the CC BY-SA 2.0 terms. The atlas was sold commercially and not for free reuse by others. The dispute was whether Drauglis' license terms that would apply to "derivative works" applied to the entire atlas. Drauglis sued the defendants in June 2014 for copyright infringement and license breach, seeking declaratory and injunctive relief, damages, fees, and costs. Drauglis asserted, among other things, that Kappa Map Group "exceeded the scope of the License because defendant did not publish the Atlas under a license with the same or similar terms as those under which the Photograph was originally licensed."^[73] The judge dismissed the case on that count, ruling that the atlas was not a derivative work of the photograph in the sense of the license, but rather a collective work. Since the atlas was not a derivative work of the photograph, Kappa Map Group did not need to license the entire atlas under the CC BY-SA 2.0 license. The judge also determined that the work had been properly attributed.^[74]

In particular, the judge determined that it was sufficient to credit the author of the photo as prominently as authors of similar authorship (such as the authors of individual maps contained in the book) and that the name "CC-BY-SA-2.0" is sufficiently precise to locate the correct license on the internet and can be considered a valid URI of the license.^[75]

This incident has not been tested in court, but it highlights a potentially disturbing practice. In July 2016, German computer magazine LinuxUser reports that a German blogger Christoph Langner used two CC-BY licensed photographs from Berlin photographer Dennis Skley ^[88] on his private blog Linuxundich.de ^[89] . Langner duly mentioned the author and the license and added a link to the original. Langner was later contacted by the Verband zum Schutz geistigen Eigentums im Internet (VGSE) (Association for the Protection of Intellectual Property in the Internet) with a demand for €2300 for failing to provide the full name of the work, the full name of the author, the license text, and a source link, as is apparently required by the fine print in the license. Of this sum, €40 goes to the photographer, and the remainder is retained by VGSE.^[76][77]

Creative Commons maintains a content directory wiki of organizations and projects using Creative Commons licenses.^[78] On its website CC also provides case studies of projects using CC licenses across the world.^[79] CC licensed content can also be accessed through a number of content directories and search engines (see CC licensed content directories).

Due to either disuse or criticism, a number of previously offered Creative Commons licenses have since been retired,^[24][80] and are no longer recommended for new works. The retired licenses include all licenses lacking the Attribution element other than CC0, as well as the following four licenses: