  Kilometer-scale neutrino detectors such as IceCube are discovery instruments
covering nuclear and partile physics, cosmology and astronomy. Examples of
their multidisciplinary mission include the search for the particle nature of
dark matter and for additional small dimensions of space. In these lectures, we
discuss the nature of cosmic neutrinos and their sources, the need for
kilometer-scale detectors and the status and methodologies of current
detectors.
