Underlying this system is the concept of The Force and the two opposing aspects, Light side and Dark side, that are reflected in how The Force is manifested in the world. This alignment resembles in many ways the aspects of morality, Good and Evil, but does not always map to the same relative ideas.
To track which side of The Force the character is leaning towards, the game uses a point system to measure actions and choices the character makes in the game world. Assigning these points to either Dark or Light based on which aspect of The Force it represented. These points are accumulated by the character and reflected on an Alignment scale on the in-game character sheet window. The scale utilizes a balance model, where neutral is in the middle and the opposite ends of the scale are a measure of Light and Dark. The difference in the amount of accumulated Light and Dark points at any point in time, pushes the character further onto one side or the other. So for example, if the character has accumulated 300 Light side points, and 700 Dark side points, his Alignment scale will show a difference indicating the character is leaning towards the Dark side by 400 points.
The Alignment scale also indicates relative levels of Dark side or Light side by side Tiers.
The most common way to gain Alignment points is to make choices during in-game dialogue from a mission sequence. Choices available during the dialog my represent Dark or Light side of the force. You can choose, in your game preferences to have an Alignment indicator appear over dialogue choices when points may be awarded for choosing a specific path in the conversation or action. You may also choose to leave off the indicator, preferring a more natural play-style and relying on your role-playing choices to gain whatever Alignment points are assigned. Keep in mind that the more familiar you are with the concepts of the The Force the more likely you are to correctly identify the actions that align to one side or the other. The Force Alignment does not simply map to Good and Evil.
If necessary, after making a dialogue choice that does not award the points you expected. You can choose to restart the dialogue to make alternate choices. You can do this by hitting escape during any point of a dialogue prior to the mission sequence's completion.
An optional mechanism to gain Light or Dark Alignment points is available through Diplomacy. Each mission assigned from this Mission Skill will award a certain amount of Dark or Light points. The mission summary will indicate which.
One interesting aspect to Force Alignment is the influence and affect it has on companion characters. Each companion in the game has various likes and dislikes. While choices you make will affect your Alignment, they will also potentially affect the affection rating you have with your companion as well. You may not always be able to make selections that award the Alignment points you desire, while also gaining Affection. In fact, depending on the companion you could lose Affection. You may need to choose, if possible, which companion is accompanying you through a mission sequence in order to get the desired combination of Alignment and Affection points. If you do not like the outcome from a choice, you might want to exit the dialogue before completion so that you can redo the mission sequence with a different companion or to make different choices.
Although the character sheet shows an Alignment scale for companions, currently, companions do not have an Alignment stat. However, often the companion's likes and dislikes reflect their actual realized Alignment in the game. It is also possible during the acquisition of a companion, such as Jaesa Willsaam, to make choices during the character's class missions that impact the actual Alignment that the character's personality will reflect in the game.
Various in-game items may require a characters Alignment of a certain Tier. These can be acquired through loot from non-player characters and creatures defeated in the game. You can also purchase these types of items from a Lightside or Darkside Vendor.