What are signs with a red background and white inscriptions used for?

Signs with a red background and white inscriptions are specifically used to denote mandatory information that must be followed by pilots and ground personnel. These signs serve crucial safety and operational purposes by indicating actions that are strictly required or prohibited, such as "No Entry," "Stop," or "Hold Short." Their prominent colors and clear markings ensure that they capture attention quickly, aiding in the prevention of accidents and ensuring proper adherence to airport rules and regulations.

By understanding that red signifies something that must be strictly observed, pilots can make informed decisions and navigate safely on the ground. This contrasts with other types of signs, which may suggest caution or provide information about services and directions but do not carry the same mandatory implications as those marked in red and white.