About the licenses
We use a number of licenses at Public Laboratory, depending on the project, the privacy a local partner needs, and whether we are licensing documentation, source code, hardware, map data, or something else.
The legal concept of the Public Domain as related to copyright is primarily within the United States, where it refers to yielding or giving up all copyright, irrevocably. This means that anyone can reuse, republish, or adapt the content, without asking permission or even attributing the authors. Works produced by the federal government of the US are supposed to be automatically released into the Public Domain. For outside the US, the Creative Commons Zero license, which attempts to be the equivalent of Public Domain, but internationally viable.
Creative Commons: "CC"
These licenses, which can be read about at the Creative Commons website, are easy-to read, thorough, and come in a few flavors, which can be mixed and matched. Much of our content is released under both Attribution and Share-Alike provisions, a combination typically referred to as "CC-BY-SA".
One of the most basic licenses CC offers, this primarily requires that you attribute where you got the content, usually with a URL and credit line.
The ShareAlike provision requires that derivative works be released under the same license. This tends to encourage users to "give back" -- sharing what they've done, re-contributing their improvements, additions, and changes back to the community. This means that any time you use, adapt, or republish content bearing this license, you must use the same license for your publication.