From Halopedia, the Halo wiki
Genetically augmented humans wearing MJOLNIR armor, the ultimate super soldier.
Spartans are the crack infantry unit of the UNSC—tough, fast moving and equipped with a rapidly recharging energy shield when not in combat. Their enhanced agility and strength enables them to leap high into the air before slamming into the ground, either to take out an enemy, place an explosive device on an enemy structure or even hijack a vehicle.
Though every Spartan has a instinctive mastery over all weapons, each of the Spirit of Fire's Red Team can be upgraded with their favored weapon. In Jerome's case this is a Spartan laser which is highly accurate and powerful, but has a slow reload rate.
Senior chief petty officer Jerome-092 was born into poverty in the infamous Palaikos borderlands on the colony world of Minister, a tough world that forced him into an early childhood of crime where he also realized his capacity for violence. He was abducted and indoctrinated into the SPARTAN-II program, where, after many initial escape attempts, he was transformed from a self-centered survivalist to a leader, honing the speed and agility that kept him alive back home.