A tool for still life photography. It is basically a translucent box that you place over your subject. Lights are pointed at the tent (from the outside of course). A hole is provided for the lens.
You can build your own tent with plastic and tent-poles, or you can buy one ready made from a company called Plume Ltd.. They call their light tent "The Coccoon"; it comes in three sizes, and it can be folded for transportation.