In the United States, the eight-sided STOP sign requires a driver to stop.
The octagonal shape is deliberately distinctive so the sign can be recognized from the back or when partly obscured by snow, darkness, or weather. The red-and-white design is now internationally familiar, although exact wording, lettering, and placement vary among countries.
At a U.S. stop sign, a driver must stop at the stop line if one is marked. If there is no line, the vehicle stops before the crosswalk, or before entering the intersection when neither marking is present. The driver then proceeds only when the way is safe and right-of-way rules permit.
A yield sign has a downward-pointing triangular shape and requires slowing and giving way, not automatically stopping. “Do Not Enter” signs are generally red-and-white rectangular signs used to mark an entrance to a one-way roadway from the wrong direction.