There are four main types of starbase:
- Military starbases, which help your ships in battle against other fleets
- Economic starbases, which increase economic and social production in the surrounding region
- Influence starbases, which encourage nearby planetary populations to defect to the owner's culture
- Mining starbases, which are used to extract a bonus affecting your entire civilization
All four kinds of starbase may also be upgraded with defensive capabilities. 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.