Creative Commons are a non-profit organisation who offer authors and rights holders a way to allow open access to their work without charging a fee. There are currently six types of Creative Commons licences available which have various reuse permissions associated. You can read more about the individual licences on the Creative Commons Website.
CC licences attach to the work and authorise everyone who comes in contact with the work to use it consistently with the licence.
CC licences range from:
permitting others to download, alter, remix and tweak your licence for commercial and non-commercial purposes; through to,
a more restrictive licence that only permits downloading and sharing of your work without making any alterations and not for any commercial use
All CC licences require you to credit the original author, licensor and/or any other party specified by the author or licensor
CC licences are not recommended for software: instead you could consider using either the Free Software Foundation or the Open Source Initiative.
Attribution of the work
The copyright holder may specify the type of attribution required. Where this is not the case, you should at least:
leave any copyright notices intact
cite the author's name, screen name, user identification, etc
cite the work's title or name, if it exists
cite the specific CC licence the work is under
if you are making a derivative work or adaptation, you need to identify that your work is a derivative work
Works in the public domain
CC licences are not intended to be applied to works in the public domain.
Applying a CC licence to a work in the public domain may constitute copyright infringement. However, if you incorporate a work that is in the public domain into a collection that is itself protected by copyright, then you may apply a Creative Commons licence to the work as a collection, although the licence will not affect the status of public domain work. Similarly, you may apply a Creative Commons licence to an adaptation of a public domain work if you hold copyright to the adaptation.
General Information
As a general rule, CC licences are made available on a royalty-free basis but there may be exceptions
CC licences are non-revocable meaning you cannot stop someone who has already gained access to your work from using it under the terms of the CC licence applying at the time it was accessed. You can stop future distributions of your work under the CC licence but it will not withdraw any copies of your work that already exist
A CC licence terminates automatically if someone uses your work contrary to the licence terms. This only applies in relation to the person in breach of the licence; it does not apply generally to the other people who use your work under a CC licence and comply with its terms.
For online works, the licence is entered into online and will include a html code in your work. This code will automatically generate a licence button and a statement that your work is licensed under a CC licence, or certify that a work is in the public domain. The html code will also include the metadata that enables your work to be found via Creative Commons-enabled search engines
For offline works, you should either:
mark your work with a statement such as “This work is licensed under the Creative Commons [insert description] Licence. To view a copy of this licence, visit [insert url]; or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California 94140, USA.”; or,
insert the applicable licence buttons with the same statement and URL link.
You can read more about Creative Commons, who they are and what their licences offer at https://creativecommons.org/