Open Educational Resources (OER) are materials for learning and teaching that are in the public domain or have been published under an open license.

Generally, there are three types of licenses: 

1. Public Domain: Free from intellectual property laws. There are no restrictions for individuals to use these works, nor are permissions necessary.
2. Open License / Creative Commons License: Author retains ownership of the work, while allowing others to use, share, and modify it without requesting permission.
3. All Rights Reserved Copyright: Author retains all rights provided by copyright law. Another person cannot reproduce, distribute and/or adapt any part of the work without permission.

THEY ARE FREE!

•  "OER improve end-of-course grades and decrease DFW (D, F, and Withdrawal letter grades) rates for all students. They also improve course grades at greater rates and decrease DFW rates at greater rates for Pell recipient students, part-time students, and populations historically underserved by higher education. OER address affordability, completion, attainment gap concerns, and learning." (https://eric.ed.gov/?id=EJ1184998)
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• “[S]tudents now spend more than $3 billion of financial aid dollars a year on course materials.” (https://studentpirgs.org/2023/02/22/open-textbooks-report/) 

More information...

Colvard, Nicholas B., C. Edward Watson, and Hyojin Park. “The Impact of Open Educational Resources on Various Student Success Metrics.” International Journal of Teaching and Learning in Higher Education 30, no. 2 (2018): 262–76. https://eric.ed.gov/?id=EJ1184998.

Xie, Dan. “Open Textbooks: The Billion Dollar Solution (2nd Edition).” Student PIRGs, February 22, 2023. https://studentpirgs.org/2023/02/22/open-textbooks-report/.