Rather than needing multiple characters to try the different classes, FFXIV lets your character switch classes, once you reach level 10. You switch classes by just equipping the weapon of the other class; each class has it's own separate level, experience meter, hunting log, etc, but as it is the same character, your quest progression and Grand Company and inventory and stuff are unaffected. Some classes have skills that can be used by other classes (for example, the Archer class has a "Raging Strikes" skill that can be used by Thaumaturge). In addition, at level 30 you can get access to advanced jobs, but only if you have leveled the correct other class to at least level 15.