Approximation Theory - Lecture notes for Part III of the Mathematical Tripos by A. Shadrin, DAMTP, University of Cambridge. (PS) A Short Course on Approximation Theory - Lecture notes for a graduate course by Neal Carothers, Bowling Green State University. (DVI,PS) History of Approximation Theory - Articles and web resources developed by Allan Pinkus and Carl de Boor. NZ Approximation Theory Group - Members, meetings, visitors and links. A View from the Back of the Envelope - About approximation and the fun it enables. Includes examples, exercises, and links to help grasp concepts such as measurement, scale and magnitude. Sections include simplifying numbers, exponential notation, Fermi problems, using your body as a ruler, and other ways to visualize size and scale. Approximation Theory - Notes for courses given by Carl de Boor, Madison. (PS) People in Approximation Theory - Amos Ron's list of links.