Function of hostapd?

[Phillip.Watts at nlynx.com]

I have built a linux router with a DLink DWL 520 pci card
as my internal interface using the hostap_pci.o as the driver
and the mode set to MASTER.

This router is now functioning as an Access Point, perfectly as
far as I can tell.(GREAT software, way to go.)

I  do NOT have hostapd loaded.  I cannot tell from the
README what its function is.  Anyone enlighten me?