  A new and powerful probe of the origin and evolution of structures in the
Universe has emerged and been actively developed over the last decade. In the
coming decade, non-Gaussianity, i.e., the study of non-Gaussian contributions
to the correlations of cosmological fluctuations, will become an important
probe of both the early and the late Universe. Specifically, it will play a
leading role in furthering our understanding of two fundamental aspects of
cosmology and astrophysics: (i) the physics of the very early universe that
created the primordial seeds for large-scale structures, and (ii) the
subsequent growth of structures via gravitational instability and gas physics
at later times. To date, observations of fluctuations in the Cosmic Microwave
Background (CMB) and the Large-Scale Structure of the Universe (LSS) have
focused largely on the Gaussian contribution as measured by the two-point
correlations (or the power spectrum) of density fluctuations. However, an even
greater amount of information is contained in non-Gaussianity and a large
discovery space therefore still remains to be explored. Many observational
probes can be used to measure non-Gaussianity, including CMB, LSS,
gravitational lensing, Lyman-alpha forest, 21-cm fluctuations, and the
abundance of rare objects such as clusters of galaxies and high-redshift
galaxies. Not only does the study of non-Gaussianity maximize the science
return from a plethora of present and future cosmological experiments and
observations, but it also carries great potential for important discoveries in
the coming decade.
