Planet: name unspecified.
The feared, leathery-skinned storm troopers genetically bred for that task by the Dominion Founders are not motivated by any of the causes of the Alpha Quadrant such as glory, nobility, politics, intrigue or even money — though they do possess a chillingly detached mercenary quality that cannot be bribed.
They are not hive-mind automatons like the Borg but are genetically bred to supreme strength and endurance, kept in line via an addiction to Ketracel-white — an enzymatic nutrient, dispensed with great ritual by each unit's Vorta, in vials which fit into the uniform and feed directly to the neck.
Military ranks are simply denoted as the First being unit leader, followed by the Second, Third, and so on; the First is answerable to the Vorta, who may reward and punish Jem'Hadar in the unit with on-the-spot promotions and demotions.
During the Dominion War a newer line dubbed "Alphans" have appeared, supplanting older Jem'Hadar types such as Gammas in being specifically bred for the Alpha Quadrant opponents while retaining the same physical appearance.
Jem'Hadar use the Dominion quick-shimmer transporter system, including an armband remote control and a personal cloaking device, or "shroud.". Their uniform also includes energy absorbing pads that can defeat a Starfleet Level 3 containment field, and a recessed collar-bone area to hold the Ketracel-white vial.
Only males are bred, gestated in birthing chambers and able to fight within three days of emergence; they mature rapidly, reaching the human equivalent of age 8 or 9 in two weeks. They do not sleep, require no food or drink except the Ketracel-white, enjoy vicious fighting, and exude superiority over all creatures except the Founders.