Speakers to monitor or PC?

My speakers are currently connected (and always have been) to my desktop PC (not monitor).

But, I keep reading that people connect their speakers to their monitor.

Not sure if this is a silly question, but what is the difference and what is best practice?

(I will be getting a new PC soon with a new monitor (w/o integrated speakers) and wish to know the best set-up)) please?

Thanks

PS - my current old monitor has no integrated speakers and these are not connected to speakers, the speakers are just connected to my PC.