Open educational resources (OER) are not just openly available and free to download, but are also licensed in a way that allows for their reuse. This reuse option is a very important part of the usefulness of OERs and is frequently referred to as the 5Rs:
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.
This work is licensed under a Creative Commons Attribution-NonCommercial 2.0 Generic License.