dark "Matter" or "Energy"?

The matter that makes up the Earth and the stars certainly seems to us the most fascinating part of the Universe. Yet it represents only the tip of the iceberg in terms of the Universe's energy content. The Universe contains five times as much apparently inert and completely invisible matter, known as dark matter. But it also contains three times as much energy in an even stranger form: dark energy. How can we measure these invisibles? And what role do they play in the history of the Universe?