Creative Commons

A CC license has three layers. The first is lawyer-readable, the second human-readable and the third machine-readable. This is to make them widely accessible.

The licenses are legal tools that can be enforced (since they work on top of copyright), so the lawyer-readable layer contain the terms and conditions that are legally enforceable in court. The human-readable layer summarise the legal code and is the most well-known layer, represented by icons. The machine-readable layer is written in a language that software can understand, called CC Rights Expression Language, and allows applications, search engines and other technologies to understand the license.

Icons (elements) used in CC licenses and what they mean:

	Attribution or “BY.” All of the licenses include this condition. It is the basic condition of all the licenses that a user provide credit to the creator.
	NonCommercial or “NC,” which means the work is only available to be used for noncommercial purposes.
	ShareAlike or “SA,” which means that adaptations based on this work must be licensed under the same license.
	NoDerivatives or “ND,” which means reusers cannot share adaptations of the work.
	The Public Domain Mark is a label used to mark works known to be free of all copyright restrictions, for example very old works where it is known the copyright has expired.
	CC0 enables creators to dedicate their works to the worldwide public domain to the greatest extent possible. Here the creator is not claiming any copyright, but rather waiving all possible rights they might have in other jurisdictions to the reproductions of their work.

The licensor (author/creator) now has different choices to make in using/combining these elements to create a specific license. There are six licenses that allow creators to share their work(s) with the public rather than reserving all rights (copyright). CC licenses apply where and when copyright applies. It does not restrict uses of works where copyright does not restrict, but it does provide creators with the means to share work with one or more of the permissions governed by copyright.

A creator can use the first four elements of CC licenses (BY, SA, NC, and ND) explained in the table above to create any of these six licenses:

	Attribution license or CC BY allows people to use a work, even if it is adapted or used for commercial purposes, as long as they give attribution to the creator.
	Attribution-ShareAlike license or BY-SA allows people to use a work, even if it is adapted or used for commercial purposes, as long as they give attribution to the creator, and share their adapted work under the same license.
	Attribution-NonCommercial license or BY-NC allows people to use a work for non-commercial purposes only, as long as they give attribution to the creator.
	Attribution-NonCommercial-ShareAlike license or BY-NC-SA allows people to use the work for non-commercial purposes only, as long as they give attribution to the creator. If they make an adaptation of the work, they must share the adapted work with others under the same license.
	Attribution-NoDerivatives license or BY-ND allows people to use the unadapted work for any purpose, even commercial, as long as they give attribution to the creator.
	The most restrictive of the licenses, Attribution-NonCommercial-NoDerivatives license or BY-NC-ND, allows people to use the work without any adaptation, for non-commercial purposes, and only if they give attribution to the creator.

Have you wondered about the differences between licence versions? Here are differences between versions 2.5 and 4.0.

Attribution:

• 2.5
  • Requirements vary by context, but the title of the work must always be included in the attribution notice. Adaptations must identify how the work has been modified. URI is only required if it contains copyright or licensing information about the work.
  • Some author were not able to request removal of attribution from uses of their work, except where it had been adapted or included as part of a collection.
  • Licenses do not explicitly state that use of the work does not equate to endorsement by the author.
• 4.0
  • The manner of attribution is allowed to be reasonable to the means, medium, and context of how the work is used. Users should note if the work has been modified (but no need to specify how). URI should always be included, where reasonably practicable to do so.
  • A user must remove attribution from a work at the author's request to the extent it is reasonably practicable to do so.
  • Users have an obligation not to imply endorsement by the author.

NonCommercial:

• The scope of permitted uses under NC licenses has remained unchanged across all versions.

NoDerivatives:

• 2.5
  • Work cannot be adapted by others, even for personal use.
• 4.0
  • Adaptations can be created as long as they are not shared.

ShareAlike:

• 2.5
  • Users must licence adaptations of SA work under the same licence (or a ported or later version, except where the work is under NC-SA)
• 4.0
  • Adaptations can also be licensed under a designated compatible licence, and this also applies to works under NC-SA.