Written by MSG Commander
Every character in your party has a Job Class. As their Job rank increases, they learn new skills specific to that particular Job.
The 3 Team Leaders each have their own unique Job Class, which cannot be changed.
Each of the Followers who joins your party starts with a specific Job Class. However, these jobs can be changed. To change jobs, just go to any chapel in any town and talk to the priest. (Note: each class change will cost you 100 Gold.)
You can change anyone's job at any time; however, when you do change jobs, you only have access to the skills for the one job you're currently holding. For example, if you have a level 7 Hunter, and you change them to a level 1 Mage, then they will lose the ability to use all Hunter skills, and can only use level 1 Mage skills (advancing in rank will unlock higher level Mage skills.)
There is one exception to this: Class Auto-Skills.
Each Job Class has a Class Auto-Skill (typically a passive support skill, which is automatically available as soon as you change jobs.)
When a Follower masters a Job Class, and then changes jobs - they retain the Auto-Skills for every Job they have mastered. Also, the first time a particular Job Class is mastered, the priest will reward you with a scroll, which will allow one Team Leader to learn that job's Auto-Skill.
Followers' Job Classes max out at level 10, so when you do master a job, it's a good idea to consider learning a new one.
In the IAP Shop "Lottery" system, some of the prizes are Animals that can join your party (Gorillas, Cats, and Owls.)
Each animal comes with is own unique Job Class, which cannot be changed (or taught to Followers). Animal Job Classes also max out at level 10.