"Open-access literature is digital, online, free of charge, and free of most copyright and licensing restrictions. What makes it possible is the internet and the consent of the author or copyright-holder." (Peter Suber, A Very Brief Introduction to Open Access)
Open Access initiatives take advantage of modern communications technology to make relevant and up-to-date scholarly information more accessible and affordable to the public worldwide. As a result, Open Access publications enjoy a wider audience. Studies in many fields show a correlation between Open Access publication and increase in citation-count ranging between 50% to 250%.
Open Access initiatives also acknowledge the public's right to access the findings of research that is paid for by their taxes. Many major publicly-funded granting agencies (for example the US National Institutes of Health, Canadian Institutes of Health Research, and the National Research Council) have adopted Open Access policies requiring that the results of funded research be made freely available in an Open Access repository.