What is a Dyson Sphere again?

A Dyson Sphere is a hypothetical structure build around a star to capture all the solar radiation for the people living around the star.  Nobody in other star systems would be able to see a Dyson Sphere star because all it's light and energy would be captured for use.

As you can see in this picture, generated by the European Space Agency, we have surrounded the Earth with fifty years of space age gear.... we are well on the way to creating a non-functional Dyson Sphere of past-tech leftovers.