U.S. road signs
Road signs in the United States follow the federal Manual on Uniform Traffic Control Devices (MUTCD): the same shapes and colors in every state. This page groups the signs by category and explains each one.
Red octagon for STOP, downward triangle for YIELD, white rectangles for regulatory signs, yellow diamonds for warnings, fluorescent yellow-green pentagons for school zones, orange for work zones and green for guide signs. On the test, questions are usually about what the driver must do when seeing the sign.