In the case of liquid crystal usually organic compound e.g. Cholesteryl nonanoate & p-azoxyanisole, the crystalline solid when heated does not melt directly into liquid state but passes through an immediate change that is called liquid crystal before changing to liquid state.

Thus liquid crystals have some properties of solids like double refraction of light, ordered arrangement of molecules or atoms. They also have some properties of liquid like surface tension flow viscosity, ordered arrangement of molecules or atoms.

Solid state $\begin{matrix} \rightarrow\\ \Delta \end{matrix}$ Liquid crystal $\begin{matrix} \rightarrow\\ \Delta \end{matrix}$ Liquid state

Liquid crystals have two phases –

Mesomorphic & Disotic –

There are three types of liquid crystals

1) Smectic or Soap like

2) Nematic or Thread like

3) Cholesteric