MapServer is a CGI based Web mapping application development tool. It processes user defined configuration files and templates to allow for a wide variety of applications to be developed, including interactive mapping, and spatial query definition and processing. It supports several data formats. Key features include scale dependent map rendering, automatic scalebar and legend building, feature labeling with collision avoidance, logical and thematic classifications, and on-the-fly projection of raster and vector data. The application can also access other WMS servers as a cascading map server.