Improvements are standard projects that can be built multiple times on each colony.
- Market Centers & Banks - Improve tax income from the planet
- Farms - Increase food production
- Embassies & Cultural Exchanges - Increase the influence of the colony
- Research Labs - Increase research
- Entertainment Centers - Increase approval in that colony
- Factories - Increase manufacturing
- Planetary Defense - Increases planet defense.
- Propaganda Center - Increases loyalty (evil only).
These can only be built once on each planet:
- Starport - Allow ships to be built.
- Orbital Fleet Manager - Allows ships in orbit to defend as a single fleet
In addition there are the following terraforming 'improvements':
You can also Decommission normal improvements.