Terran is the name of the player's race and is basically a highly evolved human. Terran may be members of any other grouping they like, even of multiple groupings where the groups allow such, but they are always considered to be ‘citizens’ of a faction; in the case that they have no faction allegiance they are said to be 'citizens of the free peoples', which is basically a neutral to all things faction in terms of political and conquest factors of the game.
Note that not all citizens are Terran - see below for race description.
Citizens, however, do define the basics for an interact-able character in the game and have traits, loyalties, relationships and cultural aspects. Relationships describe family structure and close friends; family members are usually but not always loyal to each other regardless of the actions of either one; the actions of 1 family member thus stand a chance to modify the citizen’s traits and values simulating the effects of rationalizing with regards to moral and political opinions.
Character traits play into this and are a set of defined character attributes that the citizen applies, idealizes and demonizes; these are expressed as a float between -1 and 1 i.e. an applied ‘loyalty’ trait of 0.5 with an idealized value of 1 and a demonized value of -0.5 indicates that this citizen will hate a character with a low loyalty to the point of loathing at -0.5 applied and idealizes characters with a value above their own approaching infatuation at an applied value of 1.
Citizen loyalty, not to be confused with the trait of the same name, expresses the strength of a relationship but can also be applied to factions and cultures e.g. the character may have a high loyalty toward faction A. Citizen loyalty is expressed as affection, trust, personal and published loyalty e.g. how they really feel and how they let others think they feel.
Finally citizen culture: this is an expressed grouping of similar or likeminded people. A culture, however, has no map, symbol or organization; it is simply a background or origin with defined traits which function as a modifier to the citizen’s personal traits. It is traits and the modifications to them that determine a character's prejudices and applies to the nature of considerations made by the character where applicable, such as pilots and leaders.
Note that citizen happiness can be modified by the availability of luxury items in both a positive and negative manner as well as by general availability; that is to say, citizens approve or disapprove of luxury items by time and may approve or disapprove on luxuries in general. Luxury items are stored on the foundation level of the structure system.
Terran are not the only race in the galaxy, though they are the undisputed superior race in terms of technology and capability. In terms of population they are quite few in number as they are far younger and far more war like than any other of the space faring races.
Check back here for more details on the other races of the galaxy.
Traits define the character of a citizen and govern what makes them happy, angry and so forth. Traits are applied to citizens, corporations, factions and even cultures, most often as values or virtues. Paying attention to the traits of a population or its grouping is key to managing its growth and stability.