There are 28 adventure schools that can be leveled within Istaria.
The difference to other MMO’s is that there is no restriction of how many of the adventure school a player can choose to level (if you wanted to you could join and level all 28 schools to level 100).
The adventure schools can be broken down as follows
Close proximity combat against monsters
Close or ranged magical combat against foes
A combination of melee, ranged and magical. These schools are predominately advanced schools that can be learnt after the basic adventure schools
Attack monsters from a distance using weapons such as a bow or crossbow.