The visualization component of BALL, BALLVIEW, is based on the GUI toolkit QT and on OpenGL for three-dimensional rendering. It provides an extensive set of classes for the visualization of three-dimensional geometric objects, molecules (using a wide variety of models), and surfaces. The BALLVIEW classes are QT widgets that may be integrated into any QT application. There are widgets for 3D structure viewers, for the visualization of one- and two-dimensional NMR spectra, ready-made dialogs for reading and writing molecular structures, and many more. Hence, the user's main task is the "wiring" of these components, i.e. implementing the interaction of these classes. Many more features.