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The Kardashev scale is a way of classifying how technologically advanced a civilization is. The scale originally ranged from Type I to Type III, although in recent years Type 0, Type IV and Type V civilizations have been informally added.
A Kardashev Type I civilization would be one that is able to harness all the power available on a single planet. This figure has been quoted as about 10^16 Watts, though it might be much larger. To truly harness all the power of a planet would require its disassembly and reconfiguration into a gigantic solar panel much thinner and larger than the original Earth. It would also theoretically require fusing together all atomic nuclei with a mass lower than that of iron, and fissioning all atomic nuclei with a mass greater than that of iron, in order to extract the energy. The available energy would be several orders of magnitude larger than typical guesses.
Because Earth's present-day technological infrastructure has not yet consumed all the energy on this planet, it is informally known as a Type 0 civilization. Kardashev's original definition for the threshold between a Type 0 and Type I civilization was one with an available power level of 4 x 10^12 Watts.
A Kardashev Type II civilization would harness all the power available from a single star. This figure is around 10^26 Watts, but as in the last case, it has likely been underestimated. Although one might think that a Dyson sphere, a solar panel encasing the entire sun, would be sufficient to harness all the sun's energy, to truly tap everything would require disassembling the sun and creating a lattice of mini-reactors that fuse together nuclei in the most efficient possible way. Although figures of thousands of years in the future are sometimes given for the transformation of humanity to a Type II civilization, nanotechnology and artificial intelligence might make this possible much sooner than previously expected.
A Kardashev Type III civilization would harness all the power in a single galaxy. This has been estimated at around 10^36 Watts, although Kardashev's original definition was 4 x 10^37 Watts. With the power of an entire galaxy at its disposal, a civilization would likely be able to come up with radical new power sources, perhaps extracting energy from the vacuum itself. With self-replicating space probes carrying the full set of capabilities necessary to kickstart a stellar civilization, galactic colonization could happen almost as quickly as the speed of light travels.
A Kardashev Type IV civilization would be one that consumes the power of an entire galactic supercluster. Kardashev Type V, of course, would be a civilization that occupies the entire universe.
http://www.wisegeek.com/what-is-the-kardashev-scale.htm
Edit: To help envisioning the civi's I have added examples from sci-fi
Type I
* The Pierson's Puppeteers from Larry Niven's Known Space books. Their society consumes so much power that surface temperatures are maintained by waste heat, even after the planet is moved 1/10th of a light year away from its star. Power consumption must therefore be equivalent to the previous insolation.
* All of the civilizations in BioWare's Mass Effect (series) (except for the Reapers) are somewhere in between Type 1 and Type 2.
Type II
* The People introduced in the Doctor Who New Adventures novel The Also People by Ben Aaronovitch.
* The territory of Eelong in the Pendragon Series by D. J. MacHale utilizes all power from a belt of suns known as the Skaa.
* The Culture novels of Iain M Banks contain a Type II society.
* In the Star Trek: The Next Generation episode "Relics", the Enterprise discovers an abandoned Dyson shell a special case of a Dyson sphere.
* The Imperium Of Man from Warhammer 40000, the great galactic empire with more than a million worlds at its control.
* The UNSC and Covenant as seen in the Halo series.
Type III
* Galaxia of The Foundation Series is a galaxy-spanning super-organism which combines all matter and energy in the galaxy into one being which is inherently capable of harnessing its own energy.
* In Star Maker by Olaf Stapledon. The stellar energy output of the whole galaxy is utilized by the Galactic Community of Worlds.
* Manifold: Time, by Stephen Baxter - in the distant future, descendants of humanity maintain vast Dyson nets around the supermassive black hole remnants of galaxies until they evaporate via Hawking radiation, accessing the energy equivalent of multiple galaxies.
* The civilization shown at the very beginning of the video game Xenogears, and its spiritual successors, the Xenosaga series, depict a civilization that would be a low or mid Type III civilization that has occupied about four galaxies in the local cluster. However, all of this is due to a deus ex machina, for lack of a better term, known as the Zohar Engine, that basically allowed the collective human consciousness to "make" the world they currently have possible, but this was over a 4000 year period. Xenogears however, takes place roughly about 17,000 years after the current period in which the entire civilization that grows on it's unnamed planet has based all of its technology from the remains of the 120 kilometer ship "Eldridge". The Zohar Engine took a backseat to the first several thousand years on the world, but eventually was found to be the remote lender of a near infinite power towards the end of the game.
* The Forerunners as seen in the Halo series.
* Iain Banks "The Culture" in and of themselves would constitute a mid or high Type III, but they too have civilizations the exceed them.
Type IV and above
* The backstory of The Dancers at the End of Time series by Michael Moorcock describes a civilization which consumed all the energy in all the stars in the universe, save Earth's own sun, in order to fuel an existence in which the inheritors of Earth lived as nigh-omnipotent gods.
* In a rare mention of the scale within a work of fiction, the Doctor Who novel The Gallifrey Chronicles, a Time Lord named Manual asserts that "the Time Lords were the Type-4 civilization. We had no equals. We controlled the fundamental forces of the entire universe. Nothing could communicate with us on our level."
* The Xeelee and Photino Birds from the Xeelee Sequence had power over multiple galaxies, and constructed a ring of superstrings to enter a higher dimension.
* In Futurama, exploration and settlement has expanded to the end of the universe and going so far as to destroy galaxies for fun and cross universes.
http://en.wikipedia.org/wiki/Kardashev_ ... ce_fiction
