The Kardashev scale (Russian: Шкала́ Кардашёва, romanized: Shkalá Kardashova) is a method of measuring a civilization's level of technological advancement based on the amount of energy it is capable of harnessing and using. The measure was proposed by Soviet astronomer Nikolai Kardashev (1932–2019) in 1964 and was named after him.

Kardashev first outlined his scale in a paper presented at the 1964 conference that communicated findings on BS-29-76, Byurakan Conference in the Armenian SSR (which he initiated), a scientific meeting that reviewed the Soviet radio astronomy space listening program. The paper was titled "Передача информации внеземными цивилизациями" ("Transmission of Information by Extraterrestrial Civilizations"). Starting from a functional definition of civilization, based on the immutability of physical laws and using human civilization as a model of extrapolation, Kardashev's initial model was developed. He proposed a classification of civilizations into three types, based on the axiom of exponential growth:

• A Type I civilization is able to access all the energy available on its planet and store it for consumption. Hypothetically, it should also be able to control natural events such as earthquakes, volcanic eruptions, etc.
• A Type II civilization can directly consume a star's energy, most likely through the use of a Dyson sphere.
• A Type III civilization is able to capture all the energy emitted by its galaxy, and every object within it, such as every star, black hole, etc.

Under this scale, the sum of human civilization does not reach Type I status (though it continues to approach it). Various extensions of the scale have since been proposed, including a wider range of power levels (Types 0, IV, and V) and the use of metrics other than pure power (e.g., computational growth or food consumption).

In a second article, entitled "Strategies of Searching for Extraterrestrial Intelligence", published in 1980, Kardashev wonders about the ability of a civilization, which he defines by its ability to access energy, to sustain itself, and to integrate information from its environment. Two more articles followed: "On the Inevitability and the Possible Structure of Super Civilizations" and "Cosmology and Civilizations", published in 1985 and 1997, respectively; the Soviet astronomer proposed ways to detect super civilizations and to direct the SETI (Search for Extra Terrestrial Intelligence) programs.

A number of scientists have conducted searches for possible civilizations, but with no conclusive results. However, in part thanks to such searches, unusual objects, now known to be either pulsars or quasars, were identified.