Open access (OA) scholarly works are digital, online, free of charge and free of most copyright and licensing restrictions. There are generally two ways to make scholarly works OA; open access publishing and open access self-archiving.
Open access publishing is the publication of scholarly works which is available to all potential users without financial or other barriers. This can involve the publisher charging an OA fee which is usually paid by the researcher's institution or Research Funding Council. This form of OA is referred to as 'gold OA'.
OA journals are indexed by the Directory of Open Access Journals.
Open access self-archiving is a deposit of scholarly works in an online repository or personal website which allows unrestricted access to anybody with access to the World Wide Web. Authors must read carefully any copyright agreements that they have signed if the works they are depositing have been previously published. Different publishers have different self-archiving policies. This form of OA is referred to as 'green OA'. Publisher's self-archiving and copyright policies can be searched using the SHERPA/RoMEO service.