Color change materials have been used in several very common outlets but also in an increasing number of new ones.  Commercial applications include photochromics in ophthalmics, fashion/cosmetics, security, sensors, optical memory and optical switches, thermochromics in paints, inks, plastics and textiles as indicators/sensors and in architecture, ionochromics in copy paper, direct thermal printing and textile sensors, electrochromics in car mirrors, smart windows, flexible devices and solar protection,  solvatochromics in biological probes and sensors, gasochromics in windows and gas sensors.