Space Frontier features a choice of three factions for players to pledge their allegiance to upon entering the server. Players may switch factions by simply rejoining, however an important factor to remember is that, unlike your player level, your faction level will not transfer over. Each faction has its own level that must be increased individually.
Each of the three factions have different beliefs and therefore specialise in different things.
Members of the Illumi faction fight for freedom and independence. Signified by the colour green, their guns tend to have lower recoil compared to others, and specialise in speed and accuracy.
Members of the Derept faction fight for power and control. They are recognisable by their red symbol. Their guns feature an increase in accuracy and/or walkspeed and their primary focus is speed and power.
Members of the Guard faction fight to maintain law and order. With their colour being blue, Guard guns deal more critical damage and focus on accuracy and power.
As mentioned above, each faction has its own level, similar to the player's own level. Capturing planets will award the player with reputation that goes towards the group they are aligned with at the time. Successfully increasing the level of the faction will award you with a weapon that represents it. For examples, levelling up your Derept faction will award you with a weapon that favours either impact, fire-rate, handling or a combination.