Open educational resources (OER's) are teaching and learning resources with an open licence or in the public domain.
OERs can be freely reused, modified, copied or shared.
OERs include Open Textbooks.
Choosing an open textbook for your course means:
BCcampus open textbook: a selection of open textbooks for a variety of subjects and specialties.
Mason OER metafinder: searching resources across OER specific websites.
MERLOT: curated open educational resources, including textbooks.
Open Textbook Library: hundreds of open textbooks which can be searched for or browsed by subject.
OpenStax: high-quality, peer-reviewed, openly licensed college textbooks published by Rice University.
Open textbook initiative
OASIS: openly Available Sources Integrated Search: a search tool that aims to make the discovery of open resources easier.
Teaching Commons: open educational resources from leading USA colleagues and universities.