Adopting Open Textbooks: Open Educational Resources

UN Sustainable Development Goal #4: Quality Education

"Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all"

"The "open" in open educational resources indicates that these materials are licensed with copyright licenses that provide permission for everyone to participate in the 5R activities - retain, reuse, revise, remix, and redistribute." From Defining OER-Enabled Pedagogy by David Wiley and John Hilton

The 5R's 
Retain - the right to make, own, and control copies of the content (e.g., download, duplicate, store, and manage).
Reuse - the right to use the content in a wide range of ways (e.g., in a class, in a study group, on a website, in a video).
Revise - the right to adapt, adjust, modify, or alter the content itself (e.g., translate the content into another language).
Remix - the right to combine the original or revised content with other material to create something new (e.g., incorporate the content into a mashup).
Redistribute - the right to share copies of the original content, your revisions, or your remixes with others (e.g., give a copy of the content to a friend).

Open Educational Resources consist of books, articles, images, videos, curricula, and other materials which are free to be used in educational settings, subject to certain limits, without payment. These resources exist either in the Public Domain, or under one of several types of Creative Commons license.

You can see a selection of definitions of OER from Creative Commons here.

When using OER websites bear in mind that open means open; some sites are actually commercial enterprises.