There are four main types of starbase:
- Military starbases, which help your ships in battle against other fleets. Note, that in order for the ship to receive attack or defence bonuses from a starbase, at least one weapon or defense system should be on the ship. So if you want the ship to receive an attack bonus from the starbase (be it Mass Drivers, Laser or Missiles), the ship must have at least 1 attack point in one of the three attack types (doesn't matter which one). The same thing goes for defense.
- Economic starbases, which increase economic and social production in the surrounding region. Trade routes can also be boosted by it.
- Influence starbases, which enlarge your influence area thereby increasing your influence points and encouraging nearby planetary populations to defect to the owner's culture
- Mining starbases, which are used to extract a Resource bonus affecting your entire civilization
The AI is more than willing to make its own starbases, and may take exception to the player building them too close to the AI's planets.
Starbases are limited to 4/sector, with no other restrictions on spacing. Mining starbases do not count toward this limit.
- In versions prior to v1.1, starbases cannot be built within three parsecs of each other unless each starbase is in a different sector. Mining starbases are an exception to this rule. The AI still follows the 4/sector rule.
Unless it is specified otherwise in the bonus description, starbases can influence/give bonuses only for the ships and planets that are in the influence radius of the starbase. The influence radius is visible on the main map when the starbase is selected. The bonuses from one starbase also stack with other starbases.
You can upgrade Starbases by adding Starbase modules to them, increasing their effectiveness or the effectiveness of ships in their area of effect. Starbases can have new modules added by moving a ship equipped with a Constructor module (such as the default Constructor ship) to that starbase. When the ship arrives, you can choose among a number of upgrade modules, including ones which improve the Starbase's attack, defense, harvesting, or the bonus it extends to nearby colonies or ships. All these upgrade modules need their corresponding technologies to be researched first prior to their availability.
The more starbases you already have, the more it costs to build a new one. The build cost is reduced with better logistics ability. The first four starbases are free, afterwards, the cost is calculated by the following equation:
Cost = (Starbase# - 4) * 150 * (100 - Logistics) / 100