  Gravitational wave emission is expected to arise from a variety of
astrophysical phenomena. A new generation of detectors with sensitivity
consistent with expectation from such sources is being developed. The Laser
Interferometer Gravitational-Wave Observatory (LIGO), one of these ambitious
undertakings, is being developed by a Caltech-MIT collaboration. It consists of
two widely separated interferometers, which will be used in coincidence to
search for sources from compact binary systems, spinning neutron stars,
supernovae and other astrophysical or cosmological phenomena that emit
gravitational waves. The construction of LIGO is well underway and preparations
are being made for the commissioning phase. In this lecture, I review the
underlying physics of gravitational waves, review possible astrophysical and
cosmological sources and discuss the LIGO interferometer status and plans.
