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. 
OER form part of ‘Open Solutions’, alongside Free and Open Source software (FOSS), Open Access (OA), Open Data (OD) and crowdsourcing platforms. OER are generally offered with Creative Commons licenses that allow the content to be freely reused and remixed with attribution to the original author.

Examples of OER include learning content (such as lesson plans, assignments, textbooks, exams, and videos) as well as tools for learning (like software for creating videos and websites, course management systems, and training materials).