IDL, Interactive Data analysis Language, is a complete package for the interactive reduction, analysis, and visualization of scientific data and images. Optimized for the workstation environment, IDL integrates a responsive array oriented language with numerous data analysis methods and an extensive variety of two and three dimensional displays into a powerful tool for researchers. IDL supports an extensive data import capability, publication quality hard copy output, and user-defined Motif graphical user interfaces. Users can create complex visualizations in hours instead of weeks with the aid of IDL's high level capabilities and interactive environment. IDL is useful in physics, astronomy, image and signal processing, mapping, medical imaging, statistics, and other technical disciplines requiring visualization of large amounts of data.