Open access (OA) is a set of principles and a range of practices through which research outputs are distributed online, free of cost, or other access barriers.

With open access strictly defined (according to the 2001 definition), or libre open access, barriers to copying or reuse are also reduced or removed by applying an open license for copyright.

Open access (OA) refers to online research outputs that are free of all restrictions on access (e.g. access tolls) and free of many restrictions on use (e.g. certain copyright and license restrictions).

Open access can be applied to all forms of published research output, including peer-reviewed and non peer-reviewed academic journal articles, conference papers, theses, book chapters, and monographs.

Two degrees of open access can be distinguished: gratis open access, which is online access free of charge, and libre open access, which is online access free of charge plus various additional usage rights.

These additional usage rights are often granted through the use of various specific Creative Commons licenses.

Libre open access is equivalent to the definition of open access in the Budapest Open Access Initiative, the Bethesda Statement on Open Access Publishing and the Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities.

see Intechopen

Increasingly scholars and researchers are being solicited by open access predatory journals seeking manuscript submissions and abusing the author-pays model by charging authors with publishing fees without any or proper peer review. Such questionable editorial practices are threatening the reputation and credibility of scholarly publishing. To date, no investigation has been conducted on this phenomenon in the field of rehabilitation. This study attempts to identify specific predatory journals operating in this field to quantify the phenomenon and its geographic distribution. Beall's List has been used to this end which, although not perfect, is a comprehensive and up-to-date report of predatory publishers. Of the 1113 publishers on the list, 59 journals were identified, for a total of 5610 published articles. The median number of articles published by each journal was 21, and the median amount of article processing charges was $499. Only 1 out of 59 journals was included in the Directory of Open Access Journals, whereas 7 (12%) were indexed by PubMed. Most of the publishers were based in India (36%) followed by the United States (25%) and Pakistan (5%), and 25% were without a verifiable address. The data indicate that the threat of predatory publishing in rehabilitation is real. Physiatrists, physiotherapists, researchers, and academics operating in this field are advised to use the tools available to recognize predatory practices before considering publishing in open access journals ¹⁾.