In 1964, Nikolai Kardashev, an astrophysicist involved with the Soviet SETI effort, devised the Kardashev scale: a method of measuring, on a cosmic scale, a civilization’s technological advancement based on the amount of usable energy that civilization has at its disposal.
A Kardashev Type I civilization has at its disposal all of the energy that impinges on its home planet. Using an equation suggested by Carl Sagan, humanity could be rated as a Type .7, as of the 1970s.
Not much has changed in forty years. On a cosmic scale.
A Type II civilization is any civilization capable of harnessing the total energy output of its home star. If we were to unravel the clouds of Jupiter, for instance, we could spin a globular shell one astronomical unit in radius that would be five meters thick, and trap every erg the sun beamed forth thereafter.
A rigid sphere that large would require materials far stronger than any currently known, of course. We might, instead, use swarms of orbiting solar panels to sop it up.
A Type III civilization is any civilization in possession of energy on the scale of its home galaxy. —Those civilizations which originate in dwarf galaxies or irregular clusters are at a significant advantage, here.
Type IV civilizations arbitrage speculative crises in what are to them immaterial commodities, selling short whole Local Groups. They can be detected by sudden changes in the redshift values of various economic indices.
Type V civilizations subsist entirely on the notional energy of Type I civilizations, scheming to become Type IIs. (Civilizations of Type II or better have mastered the art of radiating notional energies at frequencies too low to be heard.)
Type VI civilizations are indistinguishable from nature, and spend their time dreaming of butterflies, or are themselves butterfly-dreams—or the nearest local equivalent, of course.
(Nothing is known of Type VII civilizations. It is best not to consider them.)
When you finally come to understand dark matter, you will have the merest glimpse of the capabilities of a Type VIII civilization.
A Type IX civilization is any civilization that can successfully conceive of a Type X.