Copyright

Creative Commons licenses were created by the American non-profit organisation Creative Commons. CC licences allow authors to make their work easier to disseminate, by giving other people the right to share, use, and build on their work. There are different licences, depending on what rights each author wants to keep. Each licence is represented by a simple pictogram.

Creative Commons licences do not abolish copyright, they build on it. They simply allow creators and rights holders to decide which usage rights they want to give to the public, and which they want to keep. CC licences cannot be revoked: once a CC licence has been applied to a work, that work remains under that licence for as long as the copyright protection lasts.

CC licences are based on a combination of 4 conditions:

• Attribution (BY): the user of the work must give credit to the creator. The user must also clearly state if any changes have been made to the original work. The user must also not imply that the creator endorses or supports the changes that have been made ("non-endorsement clause").
• Share-Alike (SA): Derivative works must be distributed under the same licence as the original work.
• Non-Commercial (NC): Licensees may copy, distribute or make derivative works only for non-commercial purposes. Commercial means "primarily intended for or directed toward commercial advantage or monetary compensation."
• No Derivative works (ND): It is prohibited to adapt, remix, transform, translate or update the work, except for private use. This condition is often seen as incompatible with Open Access.
  Why Sharing Academic Publications Under "No Derivatives" Licenses is Misguided, by Brigitte Vézina, 2020

There are 7 different licences:

CC BY: The most accommodating licence. Users may distribute, adapt, translate, build upon the work as long as they credit the author for the original creation.

CC BY-SA: Users may distribute, adapt, translate, build upon the work as long as they credit the author for the original creation and licence their new creations under identical terms.

CC BY-ND: Users may reuse the work for any purpose, including commercially, credit must be provided to the author, and it can not be redistributed in modified form.

CC BY-NC: Users may reuse and adapt the work, as long as it is not for commercial purposes. They must give credit to the author. Derivative works need not be licenced under the same terms.

CC BY-NC-SA: Users may reuse and adapt the work, as long as it is not for commercial purposes. They must give credit to the author. Derivative works must be licenced under identical terms.

CC BY-NC-ND: The most restrictive CC licence. Users may not use the work for commercial purposes, they may not redistribute it in modified form, and they must give credit to the author.

CC 0: No copyright, the work is placed in the public domain. However, in many countries, including Switzerland, authors cannot waive their moral rights.

The correct way to indicate that your work is CC-licenced is to add some text that states and links to the licence, such as: "This work is licenced under a CC-BY 4.0 licence.", or, for an offline document, "This work is licenced under a CC-BY 4.0 licence. You can view a copy of this licence at https://creativecommons.org/licenses/by/4.0".  You can also add the licence button.