Spheres in Final Fantasy XI are a battle element that bestows beneficial status effects upon players as long as they are within a certain radius of the player or friendly monster that has the sphere effect; however, the sphere effect's benefit does not extend to the one who generates it. The bestowed status does not wear off with time, but it does wear off quickly once removed from the sphere's radius. Unlike buffs from other sources, sphere-bestowed buffs do not display messages in the log window when being inflicted or wearing off, and there is no visual indication that a player or friendly monster is providing a sphere.
Sphere-type effects were first added to the game with the Wings of the Goddess expansion, where they are bestowed by Mantelets—temporary defensive structures erected on Campaign battlegrounds that grant Refresh, Regen, and Regain statuses to allied troops until the Mantelet is destroyed. The Beastmen also can erect their own Mantelets, which bestow their benefits to the beastman armies instead of players. The Campaign Freelancer Titania also has a sphere that grants allied players a strong Regain.
Eventually, the addition of Voidwatch gave players access to rare special glowing armor that bestowed the Ensphere status for various stat boosts such as +Haste or +Critical Hit Rate depending on the specific armor. Furthermore, Atmacite usable during Voidwatch operations could give players even more powerful Ensphere effects such as Refresh or Auto-Reraise.