"Open Educational Resources (OER) are educational materials of any kind and in any medium that are licensed under an open license. Such a license allows free access as well as free use, editing, and redistribution by third parties without or with minor restrictions. The authors themselves determine which rights of use they grant and which rights they reserve." (UNESCO).
OER can be e.g. books, exercise sheets, lecture notes and other texts, but also photos, videos, audio files, databases, software, apps and web applications. You can find them in numerous portals and on websites. The most common open licenses are those from Creative Commons.
If you would like to use OER or license your own material, we have compiled the most important information for you below: