In designing geometry objects, the authors of ArcPy made it possible to perform geospatial operations in memory, reducing the need to use tools in the ArcToolbox for these operations. This results in speed gains, as there is no need to write the results of the calculations to disk at each step of the analysis. Instead, the results of the steps can be passed from function to function within the script. The final results of the analysis can be written to the hard drive as a feature class, or they can written onto a spreadsheet, or passed to another program.
The geometry objects are written as Python classes: special blocks of code that contain internal functions. The internal functions are the methods and properties of the geometry objects; when called, they allow the object to perform an operation (a method), or to reveal information about the geometry...