The descriptions below are meant to help understand the licenses and dedications but are not to be considered as qualified legal advice.
Public domain dedications
The most permissive way of releasing data is under a dedication to the public domain. These deeds assert that all copyright interests and database rights are waived, allowing the data to be used as freely as possible.
For the purpose of dedicating a work to the public domain Creative Commons (CC) and Open Data Commons have produced special dedications.
CC0 1.0 Universal (CC0)
CC0 1.0 Universal (CC0) dedication allows you to copy, modify, and distribute the work, even for commercial purposes, all without asking permission. Using CC0 does not imply the patent or trademark rights for the work are waived or are other associated rights, such as publicity or privacy rights. CC0 makes no warranties about the work, and disclaims liability for all uses of the work. Also CC0 indicates that using or citing the work, does not imply endorsement by the author of the work.
Open Data Commons Public Domain Dedication and License (PDDL)
Open Data Commons Public Domain Dedication and License (PDDL) is intended to allow licensees to freely share, modify, and use the work for any purpose and without any restrictions.
Creative Commons Licenses
There are six Creative Commons (CC) licenses.
Each licence includes the attribution condition. The attribution condition in the CC version 4 licences can be satisfied by a link to a Web page containing attribution information. There are three other conditions in the CC licenses and the various possible combinations produce the six licences.
For applying the attribution condition only requires the CC BY licence.
There is a Non-Commercial (NC) condition, where commercial is defined as ‘primarily intended for or directed toward commercial advantage or monetary compensation’. The three licenses that contain this condition are: CC BY-NC, CC BY-NC-SA, and CC BY-NC-ND.
The Share Alike (SA) condition inserts a copyleft clause into the licence meaning that any new works derived from the licensed one must be released under the same license. There are two licenses with the SA condition: CC BY-SA and CC BY-NC-SA.
The No Derivatives version 4 condition allows derivatives for private use, but prevents the licensee from sharing the derivations. There are two licenses: CC BY-ND and CC BY-NC-ND.
Attribution 4.0 International (CC BY 4.0)
This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation. This is the most accommodating of licenses offered. Recommended for maximum dissemination and use of licensed materials.
The full text can be found at http://creativecommons.org/licenses/by/4.0.
Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
This license lets others remix, tweak, and build upon your work even for commercial purposes, as long as they credit you and license their new creations under the identical terms. This license is often compared to “copyleft” free and open source software licenses. All new works based on yours will carry the same license, so any derivatives will also allow commercial use. This is the license used by Wikipedia, and is recommended for materials that would benefit from incorporating content from Wikipedia and similarly licensed projects.
The full text can be fount at http://creativecommons.org/licenses/by-sa/4.0.
Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0)
This license allows for redistribution, commercial and non-commercial, as long as it is passed along unchanged and in whole, with credit to you.
The full text can be found at http://creativecommons.org/licenses/by-nd/4.0.
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
This license lets others remix, tweak, and build upon your work non-commercially, and although their new works must also acknowledge you and be non-commercial, they don’t have to license their derivative works on the same terms.
The full text can be found at http://creativecommons.org/licenses/by-nc/4.0.
Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
This license lets others remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms.
The full text can be found at http://creativecommons.org/licenses/by-nc-sa/4.0.
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
This license is the most restrictive of our six main licenses, only allowing others to download your works and share them with others as long as they credit you, but they can’t change them in any way or use them commercially.
The full text can be found at http://creativecommons.org/licenses/by-nc-nd/4.0.
Open Data Commons Licenses
The Open Database License (ODbL) and the Open Data Commons Attribution License (ODC-By) are licenses designed specifically for use on databases and not on other types of material. The ODC licenses apply only to sui generis database rights (the rights to prohibit the extraction and reuse of a substantial portion of a database) and any copyright in the database structure, they do not apply to the individual contents of the database.
Open Data Commons Attribution Licence (ODC-By)
This license allows licensees to copy, distribute and use the database, to produce works from it and to modify, transform and build upon it for any purpose.
The full text can be found at http://opendatacommons.org/licenses/by.
Open Data Commons Open Database Licence (ODC-ODbL)
This license adds a copyleft condition to ODC-By that applies to new databases derived from the database.
The full text can be found at http://opendatacommons.org/licenses/odbl.
Other considerations for licensing
There are some other things that you may want to think about about if you apply a CC license to your material or use CC-licensed material.