Open access is the practice of providing unrestricted access to scholarly research by making it available for free online. It is based on the idea that information should be free and accessible to all. There are two main types of open access – gold open access and green open access.
Gold Open Access: Gold open access refers to research that is freely available from the original publisher's website, usually in the form of a digital version of the published article. These articles are usually made available with a Creative Commons license, which gives readers permission to access, download, copy, and distribute the content without having to worry about copyright.
Green Open Access: Green open access publishing allows authors to make their research available in an institutional repository or other online platform, while they still submit their work to a traditional subscription-based journal. This type of open access is also known as self-archiving, and it is typically done with a Creative Commons license. The repository or platform hosting the research must meet certain criteria in order to be certified as an “open access repository.” These criteria are set out by major funding agencies, such as the National Institutes of Health (NIH).
By sharing their work through open access, authors can promote wider readership, free of charge. This can help to increase the visibility of their work and help generate more citations for their scholarship. Furthermore, studies have found that open access articles are cited more frequently than those that are only freely available through a traditional subscription-based journal.
For more information about open access, please see this article: https://en.wikipedia.org/wiki/Open_access.