What shape is a stop sign, and what does it instruct drivers to do?

A stop sign is shaped like an octagon, and it instructs drivers to come to a full stop at an intersection. This unique shape is standardized to ensure that drivers immediately recognize the sign, even from a distance or when visibility is limited. Coming to a complete stop allows drivers to assess the intersection for other vehicles or pedestrians, ensuring safe passage. The octagonal shape is specifically used for stop signs to differentiate them from other types of road signs, which helps convey the importance of the instruction to stop. Other shapes listed serve different functions: a triangle indicates a yield sign, a rectangle can provide service information, and a diamond is used to warn of hazards, but none convey the same necessity for a complete stop.