Which color is typically used for warning signs?

The color typically used for warning signs is yellow. Yellow is universally recognized as a cautionary color, indicating that there may be potential hazards or changes in road conditions ahead. It serves to alert drivers to approach with care and to be prepared to respond to various situations, such as curves, pedestrian crossings, or construction zones.

In contrast, red is primarily used for stop signs and signals to indicate prohibitions or commands. Green is associated with permitted actions, like indicating allowed movements or directions. Blue often denotes informational signs about services or guidance rather than warnings. Therefore, yellow's specific role in signaling caution makes it the correct answer for the color used in warning signs.