Fluorescent paints glow when exposed to short-wave ultraviolet (UV) radiation. These UV wavelengths are found in sunlight and many artificial lights, but the paint requires a special black light to view so these glowing-paint applications are called black-light effects.  Fluorescent paint is available in a wide range of colors and is used in theatrical lighting and effects, posters, and as entertainment for children.
The fluorescent chemicals in fluorescent paint absorb the invisible UV radiation, then emit the energy as longer wavelength visible light of a particular color.  Human eyes perceive this light as the unusual glow of fluorescence.  The painted surface also reflects any ordinary visible light striking it, which tends to wash out the dim fluorescent glow.  So viewing fluorescent paint requires a longwave UV light which does not emit much visible light.  This is called a black light.  It has a dark blue filter material on the bulb which lets the invisible UV pass but blocks the visible light the bulb produces, allowing only a little purple light through.  Fluorescent paints are best viewed in a darkened room.
Fluorescent paints are made in both visible and invisible types.  Visible fluorescent paint also has ordinary visible light pigments, so under white light it appears a particular color, and the color just appears enhanced brilliantly under black lights. Invisible fluorescent paints appear transparent or pale under daytime lighting, but will glow under UV light. Since patterns painted with this type are invisible under ordinary visible light, they can be used to create a variety of clever effects.
Both types of fluorescent painting benefit when used within a contrasting ambiance of clean, matte-black backgrounds and borders. Such a "black out" effect will minimize other awareness, so cultivating the peculiar luminescence of UV fluorescence. Both types of paints have extensive application where artistic lighting effects are desired, particularly in "black box" entertainments and environments such as theaters, bars, shrines, etc. The effective wattage needed to light larger empty spaces increases, with narrow-band light such as UV wavelengths being rapidly scattered in outdoor environments.