This document describes the Extended Source Analysis Software (XMM-ESAS) package for the analysis of EPIC MOS and PN observations. Originally ESAS was a stand-alone package, which relied on SAS, was comprised of FORTRAN 77 routines and Perl scripts. It is now incorporated into SAS. ESAS includes routines which create source and model particle background spectra and exposure-corrected, background-subtracted (particle, soft proton, and solar wind charge exchange) images. The spectra and images are produced for user-defined regions within an observation field of view. The output files are in standard FITS format. Software for mosaicking multiple observations of not necessarily co-aligned observations is included in this package. Note: This documentation is meant to complement the document COOKBOOK FOR ANALYSIS PROCEDURES FOR XMM-NEWTON EPIC OBSERVATIONS OF EXTENDED OBJECTS AND THE DIFFUSE BACKGROUND.