The term 'daisey chain' for USB devices was once coined to describe the
manner in which many devices could be attached to a single USB port and a
second device attached to the first.
In fact I have only seen USB ports on Keyboards and Monitors, but then,
these don't daisey chain as such and work as a Hub.
The use of a 4 port USB hub will obviously accomodate 4 devices to a single
USB port on the PC, again one can attach a second 4 port hub to one of the
four ports of the first hub, giving 7 unique IO devies or 7 USB hard drives
and so on.