the limited ability to use copyrighted works without permission as determined by four factors (Nature of Use, Type of Work, Amount Used, and Commercial Impact)
in the context of openly licensed materials or open educational resources (OER), this means gratis and libre; gratis means that content and resources are provided at no cost, while libre means that people are free to do what they want with these resources
materials for teaching, learning, and research that people have free access with no cost and can legally retain, reuse, revise, remix, redistribute them
the level of license on educational resources which indicates different conditions, restrictions, or permissions users need to follow when they use or share the educational resources