Part of the "Megastructures: The Visual Encyclopedia" book project, on sale now at http://www.neilblevins.com/projects/megastructures/megastructures.htm
A Dyson Sphere would be a structure that would enclose a sun to capture the majority of its output energy. The energy could be used for various purposes, such as powering supercomputers, providing a living area for its inhabitants, and other industrial uses. It would come in three varieties: a Dyson Swarm/Ring, a Dyson Bubble, and a Dyson Shell.