The Geometry Engine Open Source (GEOS) is the C/C++ port of a subset of the Java Topology Suite (JTS) and selected functions. GEOS aims to contain the complete functionality of JTS in C++. It can be compiled on many platforms, including Python. As you will see later on, the Shapely library uses functions from the GEOS library. In fact, there are many applications using GEOS, including PostGIS and QGIS. GeoDjango, covered in Chapter 12, GeoDjango, also uses GEOS, as well as GDAL, among other geospatial libraries. GEOS can also be compiled with GDAL, giving OGR all of its capabilities.

The JTS is an open source geospatial computational geometry library written in Java. It provides various functionalities, including a geometry model, geometric functions, spatial structures and algorithms, and i/o capabilities. Using GEOS, you have access to the following capabilities—geospatial functions (such as within and contains), geospatial operations (union, intersection, and many more), spatial indexing, Open Geospatial Consortium (OGC) well-known text (WKT) and well-known binary (WKB) input/output, the C and C++ APIs, and thread safety.