More than half a century ago scientists around the world were working to learn the structure of DNA and thereby understand how it functions.Working with disparate bits of experimental data,they worked out their ideas on paper and in three dimensions; that is,they engaged in molecular modeling.The triumph of Watson and Crick was that they successfully modeled the structure of DNA,a fact that was not directly verified until decades later.For the past two decades scientists have been engaged in further modeling of DNA and other biomolecules with the aid of computer graphics and simulation.