There are various "roads" you can take when publishing Open Access. Choosing one path for a publication does not necessarily exclude other paths; depending on the situation, overlaps are possible.
Golden Road (Open Access Gold)
We speak of the golden road when publishing in a pure open access journal. Usually, the publisher charges a publication fee (Article Processing Charge, or APC). The Directory of Open Access Journals (DOAJ) collects OA journals that apply a quality assurance procedure (e.g. peer review). In the citation databases Web of Science and Scopus you will find a list of OA journals with impact factor.
Green Road (Self-Archiving/Secondary Publication)
The green road is meant when the work is also made available in an OA document server in addition to or after the original publication in a subscription journal. However, the terms and conditions of copyright and rights of use must be observed. Depending on the publisher and the journal in which the work was published, an embargo period may have to pass before the secondary publication can take place.
Many subscription journals allow both the publication of articles for which readers have to pay ("closed access") and the publication of open access articles and are thus referred to as hybrid journals.
Further types of Open Access