In this chapter, we looked at a number of important libraries for developing geospatial applications using Python. We investigated the GDAL and OGR libraries, which allow you to read and write geospatial data using a variety of formats. We also looked at how the pyproj library can be used to work with map projections and datums and how Shapely allows you to easily represent and work with geometry data. We then looked at how the Mapnik library can be used to generate good-looking maps.
While these tools are very powerful, you can't do anything with them unless you have some geospatial data to work with. Unless you are lucky enough to have access to your own source of data or are willing to pay large sums to purchase data commercially, your only choice is to make use of the geospatial data which is freely available on the Internet. These freely-available sources of geospatial data are the topic of the next chapter.