According to the way of publication: 

• The golden route: articles and contents related to them can be accessed at no cost on the journal’s website. Gold open access ensures that the final version of an article is freely and permanently accessible for everyone on the publisher’s platform, immediately after publication. Gold Open Access articles are licensed under Creative Commons Licenses (CC). This type of open access usually requires paying APC (article processing charge).  
• The green route: the full text of academic publications is deposited in a trusted repository, a publicly accessible database managed by a research organisation.
• The diamond route: publication via diamond journals/platforms that do not charge author-facing publication fees (APCs). Diamond open access journals are usually funded via library subsidy models, institutions or societies. 

According to the right to reuse: 

• Gratis Open Access – indicate material that is free of charge to read but with no additional permissions granted to redistribute, reuse or modify. 
• Libre Open Access – Libre open access is free of charge and expressly permits uses beyond fair use. These are usually granted through a Creative Commons (CC) licence.