Diamond Open Access: Open Access journals that receive financial support from institutions or other sponsors and do not charge a fee to readers or authors. Also referred to as Platinum Open Access.

Gold OA: Access through a publisher, author-pays model, in which authors are charged a fee (article processing charge, or APC) to publish their work as open access in the journal.  "Hybrid journals" offer both closed and open content, charging an APC to make content OA.

Green OA: Access through a digital repository. Institutional repositories host scholarly and creative works contributed by faculty, students, and staff of a college or university.  Other repositories, such as arXiv.org, host papers for specific disciplines only. Content in repositories often includes peer-reviewed content (publisher version or post-prints) pre-prints, dissertations, working papers and more.

Article Processing Charges (APCs): APCs are paid by authors (often through grant funds). They are used by open access journals in lieu of subscription fees to support the cost of publishing and may generate revenue for the publisher.

Direct to Open (D2O): libraries fund open access collections of ebooks through participant fees instead of purchasing individual titles or collections.  

Embargo: A period of time set by the publisher in which an academic article cannot be deposited into an institutional or other open access repository.

Hybrid Open Access: A journal or publisher that primarily provides access to articles via a paid subscription, but offers authors the option to pay an article processing charge (APC) to publish their individual articles as open access.

Predatory Publishers: Predatory publishing is an exploitative academic publishing business model that involves charging publication fees to authors without providing the editorial and publishing services associated with legitimate journals.

Publisher Policy: Publishing companies often have policies related to where and when authors can share versions of their articles.

Paywall: A paywall is a virtual "wall" behind which journal articles exist that someone must pay a fee to access. For researchers affiliated with an academic or research institution, this fee is often paid for by the institution in a subscription-based model. 

Pre-Print: A draft of an academic article as submitted for peer review.

Post-Print: The final draft of an academic article after peer review but before copy-editing.

Publisher Version: The version of an academic article that is formatted for publication in a journal and/or online.

Read & Publish Agreements: Also known as Transformative Agreements, these agreements bundle the costs of a traditional subscription (to read) with article publishing charges (to publish) under a single contract negotiated between a library and publisher.

Repository: Institutional, governmental, disciplinary or other archive that hosts scholarly research.

SPARC: The Scholarly Publishing and Academic Resources Coalition, a non-profit advocacy organization with of over 250 member libraries and academic organizations, that supports systems for research and education that are open by default and equitable by design.

Subscribe to Open (S2O): libraries subscribe to a journal collection or S2O initiative. When sufficient funding goals are met, the collections are converted to OA, and made available for public use.

Working paper: Working papers are similar to pre-prints, in that they are a draft version of a publication and have not undergone formal peer review. When posted online, they may provide an opportunity for the author to received feedback.

Adapted from UNLV University Libraries: Open Access