Namespace List
Here is a list of all documented namespaces with brief descriptions:

geos | Basic namespace for all GEOS functionalities
geom |
prep | Contains classes and interfaces implementing algorithms that optimize the performance of repeated calls to specific geometric operations
util | Provides classes that parse and modify Geometry objects
algorithm | Contains classes and interfaces implementing fundamental computational geometry algorithms
distance | Classes to compute distance metrics between geometries
locate | Classes which determine the Location of points in geometries
triangulate | Classes to compute Delaunay triangulations
quadedge | Classes to implement a topological subdivision of quadeges, to support creating triangulations and Voronoi diagrams
operation | Provides classes for implementing operations on geometries
buffer | Provides classes for computing buffers of geometries
distance | Provides classes for computing the distance between geometries
intersection | Provides classes for computing the intersection of a Geometry and a clipping Rectangle
linemerge | Line merging package
overlay | Contains classes that perform a topological overlay to compute boolean spatial functions
polygonize | An API for polygonizing sets of lines
predicate | Classes which implement topological predicates optimized for particular kinds of geometries
relate | Contains classes to implement the computation of the spatial relationships of Geometrys
sharedpaths | Find shared paths among two linear Geometry objects
geounion | Classes to perform efficient unioning of collections of geometries
valid | Provides classes for testing the validity of geometries
index | Provides classes for various kinds of spatial indexes
quadtree | Contains classes that implement a Quadtree spatial index
bintree | Contains classes that implement a Binary Interval Tree index
chain | Contains classes that implement Monotone Chains
intervalrtree | Contains classes that implement a static index on a set of 1-dimensional intervals, using an R-Tree packed based on the order of the interval midpoints
strtree | Contains 2-D and 1-D versions of the Sort-Tile-Recursive (STR) tree, a query-only R-tree
sweepline | Contains classes which implement a sweepline algorithm for scanning geometric data structures
simplify | Classes which implement algorithms for simplifying or generalizing geometries
noding | Classes to compute nodings for arrangements of line segments and line segment sequences
snapround | Contains classes to implement the Snap Rounding algorithm for noding linestrings
io | Contains the interfaces for converting JTS objects to and from other formats
WKBConstants | Constant values used by the WKB format
geomgraph | Contains classes that implement topology graphs
index | Contains classes that implement indexes for performing noding on geometry graph edges
linearref | Contains classes and interfaces implementing linear referencing on linear geometries
planargraph | Contains classes to implement a planar graph data structure
algorithm | Planargraph algorithms
precision | Provides classes for manipulating the precision model of Geometries
util | Utility classes for GEOS