Open Access is the free and unrestricted online access to publications: to read, download and re-use, subject to proper attribution. The main routes are:
- Gold Open Access: Immediate Open Access on the publisher site, usually in exchange for an Article Processing Charge (APC) or Book Processing Charge (BPC).
- There are a number of different models for journals:
- Subscription (hybrid) journals that offer a Gold Open Access option for an individual article by payment of an APC
- Gold Open Access journals which do not have subscriptions and in which all articles are Open Access, usually by payment of an APC
- Mega journals which have a broad coverage of different subjects with selection being based on sound research rather than perceived importance. They usually charge an APC.
- There is a wide range of options for publishing Open Access books and monographs, ranging from scholar led presses, learned societies and large commercial publishers. Many different models of Open Access monograph publishing are emerging. Some, but not all charge a BPC.
- Green Open Access: Depositing research in an institutional (e.g. CentAUR) or subject repository (e.g. Europe PMC). The version deposited is normally the author's final manuscript. It may be closed access on the repository for an embargo period after publication. However, major funders increasingly require immediate Open Access.
Open Access publications are licensed to indicate this status and to state how they may be re-used. Creative Commons licences e.g. the creative commons attribution licence (CC BY) are most commonly used.