Open Access is the immediate, online, free availability of research outputs without the restrictions posed by publishers to keep research hidden behind subscription journals and databases. Thus, if an article is "Open Access" it means that it can be freely accessed by anyone in the world and is free of most copyright and licensing restrictions.
Researchers can make their work open access in two ways: by depositing a copy of their published work into a Repository, like OpenUCT, or by publishing in a journal that is free to readers.
What Open Access is not
Open Access does not bypass the peer-review process; articles are peer-reviewed in the traditional manner. Some authors fear that making their work widely available will increase plagiarism, however, Open Access serves to reduce plagiarism as material that is freely available exposes plagiarism much higher.