Open access (OA) refers to freely available, digital, online information. Open access scholarly literature is free of charge and often carries less restrictive copyright and licensing barriers than traditionally published works, for both the users and the authors.
While OA is a newer form of scholarly publishing, many OA journals comply with well-established peer-review processes and maintain high publishing standards. For more information, see Peter Suber's overview of Open Access.
Source: Cornell University Library Open Access Publishing Guide
Not all open access journals and publishers are trustworthy. Check out the following resources to learn how to evaluate open access journals: