Open access is not just one way of sharing research; there are different types of open access that serve various needs and preferences in the academic community. The main types of open access include Gold, Green, Hybrid, and Diamond/Platinum open access.

1. Gold Open Access
   Gold open access is where research articles are made freely available to everyone immediately upon publication. In this model, the authors, their institutions, or funders often pay an article processing charge (APC) to cover the costs of publication. Gold open access journals are typically peer-reviewed and provide high-quality scholarly articles. Many open access journal publishers follow this model, making a wide range of research accessible to the public.
2. Green Open Access
   Green open access allows authors to share their work freely after a certain period. Researchers can publish their articles in traditional subscription-based journals but also deposit their manuscripts in open access repositories or archives. This means that while the published version might not be free, the author’s final draft or preprint can be accessible at no cost. Green access journals are vital for increasing access to academic journal articles over time.
3. Hybrid Open Access
   Hybrid open access is a combination of traditional and open access publishing. In this model, some articles in a subscription journal are available for free, while others remain behind a paywall. Authors can choose to pay an APC to make their specific article open access. This model, which includes both Gold and Green open access options, provides flexibility for researchers, allowing them to publish their work in established journals while also ensuring that it reaches a broader audience.
4. Diamond/Platinum Open Access
   Diamond or Platinum open access is a model where neither authors nor readers pay for access. In this case, funding for the publication comes from institutions, grants, or other sources. This model often features community-driven journals that provide free access to high-quality research without charging authors or readers. Open access diamond journals promote equity and inclusivity, making academic research available to all.

In summary, understanding these different types of open access—Gold, Green, Hybrid, and Diamond/Platinum—helps researchers make informed choices about where to publish their work. Each model has its benefits and challenges, but they all aim to improve access to scholarly information.