Taken from: Peter Suber's "Six things that researchers need to know about Open Access"
Open Access publications make it possible to search within all metadata and in the entire full-text. This makes them not only easier to find, but also easier to search within. This allows new approaches to scientific problems and makes the search for copyright infringements such as plagiarism easier.
Publications in Open Access will facilitate interdisciplinary and international cooperation. The access to scientific information does not depend on the profile and the financial resources of the institution. Open Access publications are also accessible in regions that were previously cut off from scientific information.
Open Access simplifies archiving of publications by scientific institutions, which are funded by the public sector. Libraries, universities and research institutions are able to archive the publications of its researchers in repositories and to make them permanently accessible. This is getting more and more important due to the increase of so-called E-only Journals that are published only electronically.
In case of documents which are published for the second time in a repository, a shift in the publishing culture can be observed. More and more publishers allow their authors a parallel publication ("green publishers"), often even without a time lag to the first publication. You will find more information about the policy of the publishers on the SHERPA / RoMEO list (for the license terms of German publishers see SHERPA / RoMEO German). Generally, it must have a different layout to the first publication. If necessary, the publication on the publisher's website has to be linked.
Furthermore, journal packages which have been licensed by Heidelberg University via the University Library may include so-called Open Access components. More detailed information can be found on the pages Current developments and Jur. Issues.
In the case of a publication in repositories like heiDOK (green road) the infrastructure is provided by the institution which is responsible for the server. For the authors the publication itself is free of charge.
If you publish in an Open Access journal (golden road), there are several options. The author funded model is financed by so-called Article Processing Charge (APC) paid by the author. In the community-fee model, institutions like universities or research centers pay fixed charges to publishing houses that allow the authors a royalty-free publication. In the consortial model, several funding bodies have built a consortium to facilitate Open Access publishing by re-directing subscription money from traditional journals to Open Access journals (as in the project for publications in High Energy Physics SCOAP3).
In many cases, Open Access Journals are also funded by academic institutions or publishers. In these journals there are no publication fees for the authors.