Ever click on the PDF for a journal article you want, only to find it you must pay a fee to access it? Open Access is a movement supported by libraries, publishers, and individuals who would like to erase those fees, making research available to everyone.
Journals that participate with open access standards provide some or all articles for free (Gold Open Access) and researchers who participate in open access standards provide free prints or preprints of their article in an online repository (Green Open Access). For an example of Gold Open Access please see the Public Library of Science journals. For example of Green Open Access search the vast theses and articles deposited in MIT’s institutional repository D-Space.