In Final Fantasy XI six basic jobs are available at the start of the game. One is chosen by the player when their character is created; this choice will decide what equipment the character starts with (e.g. mages may get a spell scroll; melees may get an extra piece of armor). After attaining level 30 in a basic job, 14 advanced jobs become available for the player to obtain, each requiring a quest to be completed first.
Players can change their job at any time by returning to their Mog House or speaking with a Nomad Moogle. These are found in major cities and minor cities, respectively. Unlike past versions of the Job System, a player does not have a separate player level and job level. A player becomes whatever level his or her job level is as each job is leveled independently.
A unique system of Final Fantasy XI's job system is the "Support Job". This system allows a player to augment their character with Abilities, Traits and Spells from another chosen job at half the level of their current job. For instance a level 20 Warrior could set Ninja as their support job. This allows them to use all Ninja Abilities, Traits and Spells up to that of a level 10 Ninja while still primarily being a level 20 Warrior. The support job system has no restrictions as to what may be set and allows for job merges never before seen in the Final Fantasy series.