Star Wars: The Old Republic fans get more information about the game's advanced classes thanks to a new article penned by Pricipal Lead Combat Designer Georg Zoeller. Zoeller talks about how the system has evolved over time, through discussions, gameplay testing and focus group input.
Advanced Classes (often abbreviated ACs) are chosen on your faction's capital world - either Coruscant or Dromund Kaas - when your character reaches level 10 or above. Each base class gets a choice of two Advanced Classes; for example if you are playing a Jedi Knight, you will be able to choose to play the Jedi Guardian or Jedi Sentinel Advanced Class.
Choosing an Advanced Class is very important in The Old Republic, as within your Advanced Class, your character will reach their full potential. Your Advanced Class choice dramatically alters the gameplay experience of your base class by providing access to two exclusive skill trees per Advanced Class, with a third being shared between both Advanced Classes.