In this appendix, you have learned the difference between the old and the new ArcGIS for Server architecture. You now know the timeline of the hardware and software enhancement that Esri has implemented during its journey of ArcGIS for Server. Server has survived the 32-bit architecture locking-trap, which ArcGIS for Desktop still suffers from and jumped into the more effective 64-bit architecture. Reworking ArcGIS for Server to utilize the 64-bit architecture has improved the software performance to a completely new level.