The most common application for liquid crystals is displays. A huge number of small size devices like calculators, watches, lab-top computer screens etc are provided with a liquid crystal display. These are not the only applications of them. They can be used as thermometers or in Optical Imaging thecnnology and also in some precise medical tool.

The liquid crystal phase was first observed in 1888 by an Austrian botanist Friedrich Reinitzer. In one of his experiments with a sample of cholesteryl benzoate he was able to see the existence of two distinct melting points for that material. At the first one, by increasing the temperature the sample passed from the crystalline phase to a hazy liquid phase. At the second critical point this liquid had a further change becaming a transparen, clear liquid.

Generally speaking a liquid crystal is not a solid and not a liquid but something in between them. It has characteristics which can be associated both with liquids and solids. There are many different types of liquid crystal and they show an unusual number of different phases. We can schematically list some of their common characteristics in the following 3 points:

1) they have a rod-like molecular structure
2) they have a rigid long axis
3) they carry strong dipoles

Other kind of liquid crystals with different shapes do exist, but the purpose of this modulus is only to give a general idea about this new phase of matter and to see how we can get displays out of it.