Alignment is one of the core character mechanics in The Old Republic, and your choice between the Light and Dark side will have a direct impact on certain aspects of your progression. In the Complete Guide to Alignment in The Old Republic we explain how the alignment system works, how you gain points on either path, and how your decisions factor into other aspects of gameplay.
As you progress down the Dark path, signs of your corruption will alter your character’s facial appearance. For example, at Dark I your character’s eye color will change to a deep orange hue, and at Dark II further signs of your corruption will be seen around the eyes and mouth as shown below.
Players also have the option to turn off visible corruption via the Preferences menu. This can be found in the Social category, and works as a simple toggle, much like the ability to show / hide your character’s head slot item.
Head over to Swtorhub.com to read the full guide: The Complete Guide to Alignment in The Old Republic