The course offers a solid introduction to students who seek principled understanding of user interfaces now and in the future. Students learn to formulate design problems and derive solutions by analysis, simulation, and optimization. The contents cover models ranging from biomechanics to vision science, psychophysics, cognitive psychology, control theory, and decision sciences. The lectures introduce the models and theories, whereas the exercises apply them to realistic problems using pen and paper, software, and hardware. Application areas cover the most widely used interfaces, including buttons, keyboards, menus, displays, visualizations, input methods, audio and multimedia systems, graphical user interfaces, and hypertext.