Release Devices
Most of us are familiar with the idea of shooting bows with three fingers and either a protective leather tab over the fingers or a leather glove of sorts. This works with longbows because of the wide angle the string takes; the fingers do not get pinched.
East of the Carpathian mountains and particularly for the little composite bows which Huns, Avars, Magyars and Mongols used from horseback, the angle of the bowstring would have been too sharp for a three-finger release. What they actually used was a thumb-ring which amounted to a release device of sorts:
The ring was grooved; the idea was that you locked the grooved part of the ring over the bow string, locked the index finger over the thumb, and then snapped the thumb loose to shoot the arrow.
Compound bows generally have a string loop behind the arrow and a mechanical release device locks the string loop and a gun-style trigger releases the arrow. Funny thing however, most release devices still use designs from ten or fifteen years ago before people started using string loops and the device locked the string itself under the arrow, with a metal nock clamped to the string just over the arrow.
There are only a couple of release devices which are basically up to date and designed for use with string loops and the one I like is the Scott Archery Silverhorn.
The trigger on that thing involves a roller bearing and is particularly precise and smooth. A certain amount of paraphernalia goes into compound bows and this is one of the more major of such items.