Supermarionation is a puppetry technique involving marionettes with extremely fine wires and electronics controlling the puppets' lip movements (a solenoid that transfered an electronic pulse to the wire attached to the bar the moved the lip) inside their heads--and later, in their chests--that synchronized the mouth movements with the vocal tracks. It is completely different from the puppetry technique used in TERRAHAWKS called Supermacromation, a Muppet-style puppetry technique, and the stop-action animation of plastic puppets in DICK SPANNER, P.I.
The early Supermarionation marionettes were made primarily of wood and leather (used as the hinge on the moving lip) and the wires were fine tungsten; as the marionettes improved over time, features got more lifelike and more properly proportioned, while plastic eyes constructed by oculists were added starting with THUNDERBIRDS for increased realism. Each marionette was between 20 and 24 inches tall; starting with STINGRAY, the marionettes often had multiple heads in order to give the impression of changing expressions (usually called the "serious face" and "smiling face") and multiple hands to be exchanged when different hand positions and gloves were needed (gloves were often merely painted hands). Later puppet bodies (second season THUNDERBIRDS and onward) replaced the wood with fiberglass, metal, and various types of plastic. Items like caps, helmets, and other headgear had wires threaded through them and were slid up the wires out of the way when not needed.
Supermarionation was first developed for SUPERCAR (though electronic lip synch and steel wire were used in FOUR FEATHER FALLS) and used for every Anderson puppet production through THE INVESTIGATOR. It was revamped between THUNDERBIRDS and CAPTAIN SCARLET; see the next question.