Like in many other 4X space conquest games, in Neptune's Pride stars are the main source of resources. They also set the victory conditions - when a player controls half of the stars in the map, he wins.
Each star has a certain number of natural resources, which determine the price of the infrastructure built on them. Higher natural resources mean cheaper construction costs. The number is enhanced by the controlling empires terraforming technology level.
Three main forms of infrastructure can be built on each star - these are Economy, Industry and Science, producing money, ships and technology points to the controlling empire. In addition, a warp gate may be built on each star and new super carrier fleets may be purchased.