"Open Educational Resources (OER) are teaching, learning and research materials in any medium – digital or otherwise – that reside in the public domain or have been released under an open license that permits no-cost access, use, adaptation and redistribution by others with no or limited restrictions." -- UNESCO. Open Educational Resources (OER). https://en.unesco.org/themes/building-knowledge-societies/oer. Accessed September 24, 2021.
For more about OER, please visit UIC's guide: