MapServer is an OpenSource development environment for building spatially
enabled Internet applications. The software builds upon other popular
OpenSource or freeware systems like Shapelib, FreeType, Proj.4, libTIFF,
Perl and others.

The MapServer CGI application provides a significant number of
"out-of-the-box" features. Here's a sampling:

* vector formats supported: ESRI shapefiles, simple embedded features,
ESRI ArcSDE (alpha release)
* raster formats supported (8-bit only): TIFF/GeoTIFF, GIF, PNG, ERDAS,
JPEG and EPPL7
* quadtree spatial indexing for shapefiles
* fully customizable, template driven output
* feature selection by item/value, point, area or another feature
* TrueType font support
* support for tiled raster and vector data (display only)
* automatic legend and scalebar building
* scale dependent feature drawing and application execution
* thematic map building using logical or regular expression based classes
* feature labeling including label collision mediation
* on-the-fly configuration via URLs
* on-the-fly projection

MapServer is not a full-featured GIS system, nor does it aspire to be.
It does, however, provide enough core functionality to support a wide
variety of web applications. Beyond browsing GIS data, MapServer allows
you create "geographic image maps", that is, maps that can direct users
to content.