PLUNDER
 
What is it ?
 
Plundering a colony basically scraps and destroys the colony, salvaging all resources from the colony. The amount you can salvage depends on the race you are currently playing. Each race has different plunder (salvage) levels.
 
Plundering colonies indirectly enables you to select which colonies you wish to keep and which ones you wish to discard. This is especially useful if you wish to get rid of useless planets found either in invading other empires or during exploration.