The new possibilities offered by the Java programming environment combined with the accessibility of the World Wide Web present new and interesting perspectives. It is thus now possible to perform simulations directly, using a Web browser, independently of the computer platform being used. Basic concepts of crystallography, Le. crystal structures, point- and space-group symmetry, lattices, reciprocal lattices and diffraction principles can be illustrated utilizing interactive simulations written in Java. A number of such applications have been developed with the aim to facilitate the understanding of these crystallographic concepts to the newcomers in the field. [References: 11]