Materials made available for teachers, students, and researchers without the barriers of cost, copyright, or licensing may be considered Open Educational Resources (OER). These materials may come in any form, such as video lectures, streaming video of performances, lesson plans, electronic books and articles, or audio files, for example.
Materials provided without cost to the user are considered Open Access Resources (OAR). There may be some limitations set on use of the materials, such as embargoes, licensing stipulations, or modification restrictions. The difference in types of Open Access, in terms of credibility and access, may be distinguished by Level.
Provided by a well-established scholarly publisher or creator without cost to the user. The
From Creative Commons, "If you’re looking for content that you can freely and legally use, there is a giant pool of CC-licensed creativity available to you. There are hundreds of millions of works — from songs and videos to scientific and academic material — available to the public for free and legal use under the terms of our copyright licenses, with more being contributed every day."