The Crystallography is a misleading term. Diamonds and relatives are on the peripheries of the crystallographer field of interest. Probably the better name would be the "structural chemistry" or even the "structural biology". How the basic structures of living, rapidly changing world are connected with something as static as crystals? If one want to know 3-D structures of biological molecules - one need to crystalize them, then to put them into the X-ray beam and to interpret the obtained diffraction pattern. For simplicity alternative techniques of structural biology, for example NMR, neutron and electron crystallography are also included here.