The class system in FFXIV is quite different than other games. There is no difference between classes and professions. There is also no limit to how many jobs you can have. Classes are broken up into three categories; Disciples of War/Magic (battle), Disciples of The Hand (crafting), and Disciples of The Land (gathering). Classes can eventually evolve into Jobs. Once you hit lvl 30 with the primary class and lvl 15 with the secondary, you will unlock a quest chain. Upon completion you will unlock your new Job. From here on out report to your Job trainer every 5 levels for a new quest.

GLADIATOR/PALADIN:  Gladiators specialize in the handling of all manner of one-handed blades, from daggers to longswords, be they single- or double-edged, straight or curved. Tracing their roots to the Coliseum, where the roar of the crowd reigns supreme, these melee combatants have learned to seamlessly flow between attack and defense in a dance that delights the eye. Making use of their skill with the shield, gladiators can also draw the attention and attacks of an enemy upon themselves, thereby protecting their comrades from harm.

MARAUDER/WARRIOR:  Marauders are combat specialists whose weapon of choice is the greataxe—a fearsome arm long associated with Eorzea's pirates. Their approach to battle is one of brute force, as they rely on pure strength and good steel to crush enemies and sunder weapons. They are highly sought after for their ferocity and intimidating presence, and are often employed to hunt down monsters plaguing the land or to turn the tide of battle between warring nations. Skilled marauders have been known to take on entire packs of slavering beasts and emerge with little more than a few scrapes and bruises.

PUGILIST/MONK:  The path of the pugilist is one of incessant training aimed at mastering the traditional techniques of hand-to-hand combat. Though pugilists command formidable power when unarmed, they are wont to use metal, leather, and bone weaponry to maximize their destructive potential. Their preference for fighting at close quarters makes negotiating distances an absolute necessity. Many among them accomplish this by avoiding burdensome armor, allowing for maximum mobility while they move in for the kill.