Open Text Book

Open Source Text-Book. An open textbook is a textbook licensed under an open Copy Right license, and made available online to be freely used by students, teachers and members of the public. Many open textbooks are distributed in either print, e-book, or audio formats that may be downloaded or purchased at little or no cost. https://en.wikipedia.org/wiki/Open_textbook

Mike Caulfield points out how important Text-Book affordability is to the State University/CommunityCollge worlds.

cf Open Education