Open access (OA) is a growing movement to make science accessible to all. It is about decreasing research that is not noticed and not used. It is also about increasing collaboration between disciplines, like pediatrics and nutrition.
When research is published behind paid access, many cannot get access to it, resulting in the research being unknown and therefore unused by many. Open access solves the problem by giving access to the research for all, thereby increasing the usage of the research and leading to further discoveries.
The video below is an interesting video that is 8 minutes and 23 seconds long, which explains open access with interesting animations. It features Jonathan Eisen, brother of Michael Eisen, one of the co-founder of Public LIbrary of Science (PLOS):