The jig in its variety of forms applied in coal preparation has been a major unit in coal washeries for one hundred years; yet the principles of jigging are still less well understood than those governing many other coal preparation unit operations. Jig control has also been viewed as an art rather than a science until recently. This review considers some of the history of jigs and the theories that have been advanced to explain their operation. Special emphasis is placed on discussion of the means of control of jigs, starting from the traditional means and working towards the novel methods that have been proposed recently. It is clear that our understanding of jigs and the means by which they will be controlled in the future will benefit from our rapidly increasing engineering computational power and will make much fuller use of microprocessor control and modern instrumentation.