During the past three decades, a variety of initiatives can be characterized as pushing for a less restrictive approach to communicating scholarship.  These may have started with the idea of "open access," but have expanded into a number of components of open scholarship:

Open Access - Publishing models that make works freely available, eliminating the cost associated with obtaining scholarly works. Open Access allows you to share your work with a broad audience free of restrictions.

Open Educational Resources - An effort to reduce dependency on the textbook model by broadening access to teaching and learning materials through resources, tools, and practices that can be fully used, shared, and adapted in a digital environment.

Open Data or Open Research - This practice recognizes the importance, in many forms of research, of preserving and making available key supporting information that does not appear in the final publication - usually data, but sometimes corpuses of examples, illustrations, mappings, software, or other materials that are difficult to publish.  These are often essential to validate the work, reproduce the work, and also can be reused in novel ways in new research and scholarship.

Open Source - A process for developing software that shares code with other developers, often solving complex problems by dividing work among separate teams. 

Some people have even begun to talk about open scholarship as a professional attitude that is less competitive, more team-oriented, and increasingly public-facing.See for example Kathleen Fitzpatrick, Generous Thinking: a Radical Approach to Saving the University.

The movement toward open access publishing became substantial in the 1990s and has become a significant and growing part of disseminating scholarship.  A concurrent and reinforcing trend has been increasingly global participation in scholarly discourse.

Penn State has recently (January 1, 2020) implemented a new open access policy that encourages the Penn State community to publish via Open Access venues whenever possible, and requires us to obtain a waiver when publishing with other outlets.  See:

Penn State also supports nation-wide “open” initiatives, such as Helios, a new (2020) consortium of 80 major universities seeking open scholarly ecologies that “would more coherently align values (why we do the work we do), practices (how we do that work), and incentives (how we are recognized and rewarded).”