There are two main and non-mutually exclusive routes to Open Access::
'Green' Open Access (also called self-archiving)
- The authors archive (self-archiving or by a third person), in an open repository, the final version of the article or the final manuscript peer-reviewed.
- It can be deposited before, during or after the publication. Usually it is archived after an embargo period set by the publishers whose review and publishes the article in journals.
- Usually the commercial publisher's version is immediately available upon payment, during the embargo period, through subscriptions or fees for view / downloads.
- Both versions have the same content (peer reviewed), but may have a different format.
- This model is promoted by the majority of open access community formed by researchers and librarians.
‘Gold’ Open Access (also known as Open Access publishing or author pays publishing):
- The publication is immediately made available in Open Access by the scientific publisher. Research articles are accessible since they are published.
- The publication costs are covered by the authors (the university or research centre to which the researcher/author is affiliated, or to the funding agency which has financed the research).
- This model is usually the one promoted by the community of.scientific publishing
- Some journals, called hybrid journals, subscriptions and publications offer Open Access to certain articles.
Most well-established publishers have adapted to the research community's interest in publishing in Open Access mode, yet usually in favour of 'Gold' Open Access.
Nevertheless, a large number of journals, including those with high prestige and/or high impact factors have also developed self-archiving infrastructures ('Green' Open Access) that are compatible with the policies of research funding bodies such as the Commission for Horizon 2020.