Part of the surface of clothes may be made retroreflective (small parts of coats, large parts of special safety clothes for rescue workers etc.). This way they become much more visible in the dark for observers near a light source, such as the driver of a car with its headlights on. The pattern of the retroreflecting parts also helps to distinguish between objects and people.
For greater visibilty at daytime, as well as for decoration, very bright colors are obtained with fluorescence.
The opposite are clothes with a camouflage pattern.
Many Halloween costumes are considered high-visibility, as they have reflective strips sewn into the fabric.