What do white characters on a yellow background stand for?

Important road conditions. Netease official website information shows that black and white characters on a yellow background tell you the important road conditions ahead, such as the railway ahead. The specifications, colors and fonts of road traffic signs are uniformly stipulated by the Ministry of Communications, which are not only eye-catching, but also have different meanings: black patterns with yellow background and black edges are warning signs; White background, red circle, red bar, black pattern and pattern layering are prohibited signs; The color of the indicator is blue background and white pattern; Blue background and white pattern are guiding signs.