Jmol is free, open source software for interactive molecular visualization. Since it is written in the Java[TM] programming language, it is compatible with all major operating systems and, in the applet form, with most modern web browsers. This article summarizes Jmol development and features that make it a valid and promising replacement for Rasmol and Chime in the development of educational materials, as well as in basic investigation of biomolecular structure. The description is set up by comparison with the well known abilities of Rasmol and Chime. Jmol is suitable for molecular model display and analysis in biochemistry, molecular biology, organic and inorganic chemistry, crystallography, and materials science.