OER are teaching, learning, and research resources that reside in the public domain or have been released under an intellectual property license that permits their free use and re-purposing by others. ~ William & Flora Hewlett Foundation
For a more comprehensive overview on OER, see:
"Used Punch Card." By Pete Birkinshaw. Taken on November 6, 2010. Attribution 2.0 Generic (CC BY 2.0). Until the mid-1970s, punch cards were used to load software into mainframe computers. Users were warned: "Do not fold, spindle or mutilate" the cards.
Here are several OER Computer Science and Information Technology textbooks and course materials. Additional OER may be found by searching the resources listed on the ACC Libraries primary Open Educational Resources Guide.