What are the Firmware?

What are the firmware listed at http://firmware.us.ardupilot.org/Copter/? How are they to be used?
I have a pixhawk in a Y6

Hi Donald,

I’m not sure what answer you are looking for. The firmware listed at that link is the firmware we build regularly from master (everyday development) as well as stable and beta versions, for several boards and frame types.

If you aren’t comfortable looking in there for what you need then you should use a Ground Control Station (GCS) that can help you choose the correct firmware for your board.
There are several GCS: