Open Educational Resources/Historical/Copyright

OER are often characterised by use of certain licences, although this is not a part of their definition. The licencing of OER is rather wide and includes but extends beyond copyleft and free software. Resources which are widely recognized as OER, such as MIT's OpenCourseware, use licences such as CC-BY-SA-NC (a Creative Commons licence which requires attribution, adherence of modifications to the same licence, and restricts to non-commercial use).

In general, OER tend to carry one of the following licences:
 * most commonly, any Creative Commons licence
 * GFDL
 * public domain

It is conceivable that other licences could be used if they achieved similar results, but it is considered good practice to aim for compatibility and standardisation with licensing. The most important criteria of OER licences is that they should permit However there are no precise definitions.
 * 1) an indefinite chain of distribution without further permission and
 * 2) promote re-purposing.

A higher degree of openness concerning licenses relates to the freedom to make and redistribute copies, in whole or in part, of the information or expression.