The Kardashev scale is a proposed hypothetical scale for categorizing a civilization's level of technological advancement proposed by Russian astrophysicist Nikolai Kardashev. The Kardashev scale is based on the total amount of energy a civilization would be able to harness and use for communication, such as laser or radio communication. Even if a civilization doesn't purposely use energy to communicate it would still be making its existence known through energy leakage and infrared radiation.

The Kardashev scale has three official categories:

• A Type I civilization (planetary civilization) can harness and store all of the energy which reaches its planet from its parent star. This can be done by utilizing nuclear fusion reactors.

• A Type II civilization (stellar civilization) can harness and control the total energy of its parent star. This can be done hypothetical by utilizing a Dyson sphere.

• A Type III civilization (galactic civilization) can harness and control energy on the scale of its entire home galaxy. This can be done hypothetical by using a combination of Type I and Type II civilization technologies along with harnessing the power of a supermassive black hole.

Various extensions have been proposed to the Kardashev scale but are not yet as widely accepted.

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