The term "Open Access" was introduced by the Budapest Open Access Initiative in 2002 and reads as follows:

By “open access” to [peer-reviewed research literature], we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.

Open Access was initially focused on providing free online access to peer-reviewed articles in scientific journals.The concept and practice of Open Access have constantly expanded and can also be used to refer to unrestricted access to various types of scholarly publications, including monographs and edited books, research reports, theses or underlying research data.

Generally speaking, an Open Access publication is characterized by the following aspects: it is publicly available on the internet, anyone can read it free of charge, download it, and use it in any legal manner, as long as the publication is referenced and cited correctly. Open Access does not mean, however, free access for faculty and students to conventional journal articles in the eJournals in the WU catalog or to the databases. Access to these resources is paid for by WU.