Open Educational Resources 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. 
Open educational resources give educators the ability to adapt instructional resources to the individual needs of their students, to ensure that resources are up-to-date, and to ensure that cost is not a barrier to accessing high-quality standards-aligned resources. 
According to SPARC:
The key distinguishing characteristic of OER is its intellectual property license and the freedoms the license grants to others to share and adapt it. If a lesson plan or activity is not clearly tagged or marked as being in the public domain or having an open license, it is not OER.
This LibGuide was created by Angela Davis, Instruction and Web Services Librarian, as part of professional development sessions held for the faculty of Pitt Community College on September 26 & 27, 2018.
Reused and adapted here by permission.