"Open Access stands for unrestricted access and unrestricted reuse. With Open Access, researchers can read and build on the findings of others without restriction. Much scientific and medical research is paid for with public funds. Open Access allows taxpayers to see the results of their investment. Open Access means that teachers and their students have access to the latest research findings throughout the world." Source: Public Library of Science.
There are a number of types or levels of open access. This is often determined by individual publishers.
This video was created by Natalie Ross and Anna Standish. https://creativecommons.org/licenses/by/4.0/
SPARC (Scholarly Publishing and Academic Resources Coalition) Director of Programs and Engagement Nick Shockey and Professor Jonathan A. Eisen talk about the impact of Open Access. https://creativecommons.org/licenses/by/4.0/.