Peter Suber. Open Access Overview. 2007. [doi]
This is an introduction to open access (OA) for those who are new to the concept. I hope it's short enough to read, long enough to be useful, and organized to let you skip around and dive into detail only where you want detail. It doesn't cover every nuance or answer every objection. But for those who read it, it should cover enough territory to prevent the misunderstandings that delayed progress in our early days.