Default beep - what decides it?

On this XP Pro PC the 'Default beep' sound is currently set in CP
Sounds and Audio Devices Sounds as Ding.wav. I haven't noticed it
much before but I recall it occurs when I do something obviously
dis-allowed, like trying to type text where it's invalid, etc.

But sometimes I'm hearing it when I don't expect it and it seems
inappropriate. What are the rules here please? Presumably it can be
programmed in each application? But are there any 'Windows' operations
on top of those?

--
Terry, East Grinstead, UK