An educational resource can be anything - videos, presentation slides, recorded lectures, textbooks.
They can come from a range of sources.
Open licences, such as Creative Commons, allow us to adapt and blend different resources. A CC licence describes the exact conditions of the re-use and distribution of the material. It means you don't have to request permission to do anything that is allowed in the licence.
Common conditions:
Share Alike - means you must attach a Share Alike CC licence to the material you've embedded the CC material in (like I've done with this presentation).
Non-commercial - must not be used/on-sold for profitable purposes.
No Derivatives - means you can't change any of the content - you must use it as it is, in its entirety.
See
creativecommons.org/licenses for full information.