This book emphasis on introduction of calix[4]arene and its applications in various fields such as liquid crystlas, fluroscence sensor and bio-active molecules.Calix[n]arenes are cyclic oligomers obtained by the condensation of phenol and formaldehyde under basic conditions, and they occupy a privileged position in supramolecular chemistry. calix[4]arene is the most efficient molecule in current area of research.