Need some help understand the class/job system

[Shougun]

Thank you both for you're answers they were very helpful, but they did spark a new question, are all abilities cross class or is it only specific ones?

Only specific ones, when you hover your mouse over an ability it will read which classes and jobs can use it.

Here is a fun list: http://www.ffxivguild.com/ff14-cross-class-skill-guide/

The Guide is a little old but should still be fairly accurate, you can also see specifics by going at the top and going through the menu job > black mage > cross class: http://www.ffxivguild.com/ff14-black...-skills-guide/