Table 2.

Types of open access publishing

Type	Definition
Gold[14]	In this type of open access, the journal may choose to take APCs from the author and after peer review and publication, the article is freely available on the internet and anyone is free to download and read it. Such journals allow unrestricted access to all the articles in their archives
Hybrid[16]	In this type of access, the journal publisher offers the option to the author of choosing to pay APCs to make his/her research freely available after acceptance and publication or to not pay APCs and make his work accessible to readers only through subscription or institutional access
Green[15]	In this the journal, publisher allows the author to self-archive research articles in institutional repositories and then provide free access to their own work through the archives. From this independent repository, people can download the content free of cost. This type of open access is author specific and the reader may not be able to access all the articles included in that journal
Bronze[17]	These articles are free to read on the publishers page but cannot be downloaded and reused, due to the lack of a clearly identifiable license
Diamond or platinum [18,19]	This is a type of open access publishing with free and unrestricted access as in gold open access, but the publisher does not charge any APCs from the authors
Black[20]	Unauthorized copying of digital content and its dissemination either through social media sites (for e.g., the ICanHazPdf) or through dedicated websites like Sci-Hub. This is a rather large scale implementation of the practice in which someone with access to paywalled literature would download it and disseminate it among his contacts
Libre[21]	The paper is made available under an open licence allowing it to be shared and reused
Gratis[21]	In this type of open access, the paper in the journal is free to read. However, sharing and reuse are not permitted and are protected by copyright

APCs: Amount of article processing charges