What is OER...and what is it NOT
OERs are not just free content. There is much of such materials in the digital and non-digital world that can be accessed, but the author or organization retains all rights. For example, you may read an article for free but you might not be able to share print or digital copies to others. It’s free to consume, and that’s all. OERs are different.
To use OER content, you need to know which Creative Commons licenses are assigned to the content. Here are some content that gives explanation from Creative Commons: