Even without a working knowledge of astrophysics, the term supernova conjures up a vision of an almighty stellar explosion, even amongst non-astronomers. The term was first used by Fritz Zwicky (1898–1974) and Walter Baade (1893–1960), two pioneers of the photographic era. Zwicky himself was, by all accounts, a somewhat abrasive character who once stated that the other astronomers at the Mount Wilson Observatory were “spherical bastards.” When asked to explain the use of the word “spherical,” he allegedly explained that they were bastards when looked at from any angle! Abrasive or not, Zwicky was the first obsessive supernova hunter, and his vision of these events being almighty stellar explosions was accurate; indeed, an explosion on the scale of a supernova is truly beyond our capacity to comprehend. All one can do is juggle with huge numbers, containing endless zeroes, and pretend we understand the scale of events involved. But before we look at what a supernova really is, let us explain a few basic concepts here so that readers who are relatively new to astronomy will not get lost.