Creative Commons Licenses
Most OERs have a Creative Commons license on them. Creative Commons (CC) licenses allow the creator of a work to change the copyright from "all rights reserved" to "some rights reserved". There are a variety of CC licenses authors can choose from and they can be mixed and matched as needed. Many of the licenses allow users to edit the materials and customize them for a different use. Most of the licenses require users to provide credit to the original creator. Some licenses specify that you can remix and reuse, but not for commercial purposes. And there is also an option for limiting the creation of derivative works (although that wouldn't be considered OER anymore). The main CC licenses are listed below, but the Creative Commons website has more useful information about license specifics, and their License Chooser tool is especially helpful for navigating the decisions to make and generating a license for your work.
All images courtesy of Creative Commons.
Attribution (BY)
Attribution (BY) - NonCommercial (NC)
Attribution (BY) - ShareAlike (SA)
Attribution (BY) - NonCommercial (NC) - ShareAlike (SA)
Attribution (BY) - NoDerivatives (ND)
Attribution (BY) - NonCommercial (NC) - No Derivatives (ND)