A preprint of my book chapter "What Is Open Access?" is now available. This chapter provides a brief overview of open access (around 4,800 words). It examines the three base definitions of open access; notes other key OA statements; defines and discusses self-archiving, self-archiving strategies (author Websites, disciplinary archives, institutional-unit archives, and institutional repositories), and self-archiving copyright practices; and defines and discusses open access journals and the major types of OA publishers (born-OA publishers, conventional publishers, and non-traditional publishers). It will appear in: Jacobs, Neil, ed. Open Access: Key Strategic, Technical and Economic Aspects. Oxford: Chandos Publishing, 2006. It is under a Creative Commons Attribution-NonCommercial 2.5 License.