The core of every liquid crystal display (LCD screen) lies in a remarkable substance – the liquid crystal. It is neither a simple liquid nor a solid, but rather a "fourth state" of matter existing between the two. As temperature changes, liquid crystals transition through an intermediate state that appears turbid, yet their optical and electrical properties remain similar to those of crystals, exhibiting anisotropy and birefringence. It is this dual nature, combining the fluidity of liquids with the ordered structure of crystals, that enables the precise control of light through an electric field, forming the physical foundation of the entire liquid crystal display industry.