A clutch is a device that can engage and disengage a power transmission. When the transmission power has to be controlled, either in amount or over time, the clutches are here to do their job.
A multi-plate clutch, as the name suggests, has more than one driven plate. This type of clutches has been mostly used on cars up to about 1930. The single-plate clutch has several advantages over the multi-plate one as it can disengage the drive.
Nevertheless, multi-plate clutches find a use in automatic gearboxes. Here they hold various gear elements which makes them more suitable.