The Job System is the heart of Final Fantasy Tactics. Each character can learn abilities from various jobs, and these abilities can be equipped as primary, secondary, reaction, support, and movement skills. To unlock new jobs, characters must accumulate Job Points (JP) in their current job and meet specific prerequisites (e.g., Squire Level 2 to unlock Knight).
JP is earned by performing actions in battle. Experiment with different jobs early on to understand their strengths and weaknesses. Don't be afraid to switch jobs frequently; learned abilities are permanent and can be used with any job. This flexibility allows for incredibly diverse and powerful character builds.